POR6  STRT 


HOUSTON 


o 


OUTLINES  OF  FORESTRY; 


OR, 


THE   ELEMENTARY   PRINCIPLES 

UNDERLYING  THE  SCIENCE 

OF  FORESTRY. 


BEING  A  SERIES  OF  PRIMERS  OF  FORESTRY. 


BY 

EDWIN  J.  HOUSTON,  A.M., 

MEMBER   OF   THE   PENNSYLVANIA  FORESTRY   ASSOCIATION,   PROFESSOR  OF  PHYSICS 
IN    THE    FRANKLIN    INSTITUTE    OF    THE    STATE    OF    PENNSYLVANIA,    PRO- 
FESSOR  OF    NATURAL    PHILOSOPHY   AND    PHYSICAL    GEOGRAPHY    IN 
THE  CENTRAL  HIGH  SCHOOL  OF  PHILADELPHIA,  ETC.,  ETC. 


PHILADELPHIA: 

J.  B.  LIPPINCOTT  COMPANY. 
1893. 


COPYRIGHT,  1893, 

BY 
J.  B.  LIPPINCOTT  COMPANY. 


GUv- 


r 


Main 
Agric. 


PRINTED  BY  J.  B.  LIPPINCOTT  COMPANY,  PHILADELPHIA. 


PREFACE. 


WHEN  from  any  cause  a  necessity  exists  in  any 
country  for  the  removal  of  its  forests  from  ex- 
tended areas,  unless  care  be  taken  as  to  the  man- 
ner in  which  such  removal  is  made,  and  some 
parts  are  left  wooded,  irreparable  injuries  will 
inevitably  follow. 

In  the  United  States,  where  the  enormous  in- 
crease in  population  has  resulted  in  the  removal 
of  the  forests  from  extended  areas,  such  intelli- 
gence and  care  have  unfortunately,  in  most  cases, 
not  been  exercised.  The  timber  lands  have  gen- 
erally been  purchased  at  figures  based  almost 
entirely  on  the  value  of  the  standing  wood.  The 
trees  have  been  cut  down  in  a  reckless  manner, 
and  fires,  carelessly  started,  have  often  been  left 
indifferently  to  burn  themselves  out.  No  attempts 
have  been  made  to  protect  the  soil  that  has  been 
denuded  of  its  natural  protective  covering  by  the 
axe  or  the  fire.  Before  the  forest  has  been 
made  to  yield  its  entire  harvest,  the  greed  of  the 

3 


4        I  -'.v'rV  '{   tJfBJQ^Efii 

speculator  has  too  often  led  him  to  abandon  to  the 
destructive  action  of  the  elements  the  area  he  has 
thus  despoiled,  in  order  to  seek  another,  as  yet 
unbroken,  forest  area. 

Instead  of  carefully  removing  some  of  the  trees 
from  the  forest,  and  leaving  the  area  in  such  a 
condition  as  to  enable  it  to  produce  a  new  growth, 
in  the  United  States  it  has  too  frequently  been 
the  case  that  the  virgin  forest  is  thoughtlessly 
attacked,  its  best  trees  cut  down  in  so  careless  a 
manner  that  the  harvested  crop  amounts  to,  per- 
haps, but  a  third,  or  even  less,  of  the  total  growth, 
and  the  remaining  part  abandoned  to  certain 
destruction  by  the  elements. 

The  irreparable  loss  caused  by  such  greed  should 
be  prevented  by  the  enactment  of  judicious  penal 
laws. 

It  is  often  very  difficult  to  persuade  the  general 
public  that  evil  results  following  any  course  of 
action,  which  do  not  come  immediately,  are  not 
thereby  prevented  from  coming  eventually.  Be- 
cause the  evil  day  draws  not  nigh  quickly,  there 
is  a  tendency  to  believe  that  it  will  never  come  at 
all. 

An  attempt  has  been  made  in  the  "  Outlines  of 
Forestry"  to  point  out  to  the  general  public,  in 


PREFACE.  5 

simple,  non-technical  language,  the  character  of 
the  effects,  both  on  the  general  climate  of  a  coun- 
try and  on  the  distribution  of  its  rainfall,  which 
inexorably  follow  the  unsystematic  removal  of  its 
forests. 

It  is  only  necessary  to  give  the  public  some  little 
insight  into  the  effects  produced  by  the  destruction 
of  the  forest  to  arouse  it  to  a  conviction  of  the 
necessity  for  the  existence  of  "Forestry  Associa- 
tions," for  the  enactment  of  laws  regulating  the 
manner  in  which  the  forests  shall  be  removed, 
and  for  the  setting  aside  of  certain  districts  on 
which  forests  shall  be  perpetually  maintained. 

In  order  to  enable  the  readers  of  this  little  book 
to  carry  their  reading  beyond  the  elementary  prin- 
ciples which  it  discloses,  appropriate  extracts,  taken 
from  standard  authors,  and  published  by  permis- 
sion of  the  authors  or  publishers,  have  been  added 
at  the  end  of  each  primer.  In  all  cases  the  exact 
title  of  the  book  has  been  given,  as  well  as  the 
names  of  its  publishers. 

For  general  aid  in  remembering  the  princi- 
ples discussed  in  each  primer,  a  concise  review 
has  been  given  at  the  close  of  the  book  in  the 
form  of  a  primer  of  primers. 

The  author  has  not  hesitated  to  consult  freely 
1* 


6  PREFACE. 

all  standard  authorities  in  matters  pertaining  to 
the  general  subject  of  forestry. 

There  have  been  added  to  the  book,  in  the  shape 
of  an  appendix,  lists  of  trees  suitable  for  planting 
in  different  sections  of  the  United  States,  as  fur- 
nished by  eminent  authorities  on  the  subject. 

The  author  desires  to  express  his  thanks  to  the 
gentlemen  who  have  responded  to  his  circular 
letter  of  inquiry  as  to  lists  of  trees  suitable  for 
replanting  in  various  sections  of  the  United  States, 
and  to  his  friend  Professor  Charles  S.  Dolley  for 
revision  of  the  manuscript  of  this  book. 

EDWIN  J.  HOUSTON. 

CENTRAL  HIGH  SCHOOL,  PHILADELPHIA,  PA., 
January,  1893. 


CONTENTS. 


FAGS 

I. — FORESTRY 9 

II. — CONDITIONS  NECESSARY  FOR  THE  GROWTH  OP 

PLANTS 20 

III.— THE  WIDE  DISTRIBUTION  OF  PLANT  GERMS    .  32 
IV. — CONDITIONS   NECESSARY  FOR  THE  GROWTH  OF 

TREES 42 

V. — THE  FORMATION  OF  SOIL 50 

VI.— THE  INANIMATE    ENEMIES  OF  THE  FOREST  .   .  61 

VII. — THE  ANIMATE  ENEMIES  OF  THE  FOREST  ...  71 

VIII. — THE  DESTRUCTION  OF  THE  FOREST 81 

IX.— THE  EARTH'S  OCEAN  OF  VAPOR 90 

X.— KAIN 100 

XI.— DRAINAGE 109 

XII.— CLIMATE 119 

XIII. — CLIMATE  AS  INFLUENCED  BY  THE  PRESENCE  OF 

THE  FOREST 127 

XIV.— PURIFICATION  OF  THE  ATMOSPHERE 140 

XV.— HAIL 147 

XVI.— KEFORESTATION  AND  TREE-PLANTING    ....  155 

XVII. — THE  BALANCE  OF  NATURE 164 

XVIII.— PRIMER  OF  PRIMERS 177 

APPENDIX 209 

INDEX 245 

7 


OUTLINES   OF   FORESTRY. 


I.  FORESTRY. 

THE  science  of  forestry  not  only  treats  of  the 
care  and  preservation  of  those  parts  of  the  earth 
that  are  covered  with  trees,  but  also  of  the  means 
best  suited  to  the  replanting  of  the  areas  from 
which  the  trees  have  been  removed. 

If  nature  is  let  alone  she  will  cover  any  por- 
tion of  the  earth  where  vegetable  life  is  possible 
with  the  particular  kind  of  vegetation  best  fitted 
to  grow  under  the  existing  conditions  of  soil,  heat, 
light,  and  moisture. 

Nature  will,  therefore,  cover  with  forest  all  por- 
tions of  the  earth  where  forests  are  best  fitted  to 
exist. 

It  may  then  be  asked,  on  what  does  the  science 
of  forestry  rest  ?  "Why  not  leave  nature  alone  ? 
Such  questions  arise  from  a  misunderstanding  of 
what  forestry  endeavors  to  accomplish.  Forestry 


10  OUTLINES  OF  FORESTRY. 

does  not  aim  to  oppose  nature,  but  simply  to  aid 
her.  It  endeavors  to  make  use  of  the  conditions 
naturally  existing  in  any  locality  that  are  favorable 
to  the  continued  growth  of  trees,  and  to  oppose 
or  hold  in  check  conditions  unfavorable  to  such 
growth. 

The  following  considerations  will  suffice  to  show 
the  necessity  for  the  existence  of  Forestry  Associa- 
tions, and  the  enactment  of  strict  laws  for  the  care 
and  preservation  of  the  rapidly  decreasing  forest 
areas  of  the  earth.  The  North  Temperate  zone, 
the  cradle  of  the  human  race,  possesses  the  densest 
civilized  population.  This  zone  was  originally 
covered  by  extensive  forests,  and  is  still  heavily 
wooded  over  extended  areas. 

Civilized  man,  however,  cannot  continue  a 
dweller  in  the  forest.  It  is  true  that  in  sparsely 
settled  districts  no  necessity  exists  for  the  removal 
of  the  entire  forest ;  but,  as  the  density  of  popula- 
tion increases,  the  demands  made  on  the  forest 
increase.  Such  demands  will,  therefore,  increase 
rather  than  decrease  in  the  near  future.  Hence 
the  necessity  for  the  existence  of  Forestry  Associa- 
tions and  the  enactment  of  Forestry  Laws. 

The  demands  made  on  the  forest  by  civilized 
man  are  either — 


FORESTRY, 


11 


1.  For  the  area  on  which  the  forest  stands,  or 

2.  For  some  of  the  products  of  the  forest,  such 
as  wood  for  huilding  purposes  or  fuel,  or  bark  for 
the  tannery. 

The  demands  for  the  areas  on  which  the  forests 
stand  are  made  either  for  the  purpose  of  increas- 
ing the  extent  of  the  agricultural  areas,  or  for  the 
building  of  ordinary  roads  or  railroads. 

We  may  tabulate  these  demands  as  follows : 


1.  For  land  to  be  cultivated  for 
ordinary  farm  products. 

2.  For  the  construction  of  ordi- 
nary roads  or  railroads. 


1.  Fuel. 

2.  Charcoal. 

3.  Building  purposes  generally. 

4.  Fences. 

5.  Railroad  ties. 

6.  Telegraph  poles. 

7.  Mining  purposes. 

8.  Bark  for  tanneries. 

9.  Turpentine,  rosin. 


When  the  forests  are  removed  for  the  area  on 
which  the  trees  stand,  the  destruction  is  necessarily 
complete. 

Where  the  removal  is  for  agricultural  purposes, 


r  1.  Area  on 

which  it   - 

stands. 

Encroachment 

on  the  forest 

for— 

2.  For  its 

products. 

12  OUTLINES  OF  FORESTRY. 

the  destruction  should  not  be  complete.  The  prin- 
ciples of  forestry  teach  that  the  truest  economy 
will  permit  certain  tracts  to  remain  covered  with 
trees;  for  the  ultimate  gain  to  the  farmer  from 
such  a  course  will  be  greatly  in  excess  of  the 
sums  paid  for  rental,  or  the  interest-charges  on 
the  land  that  is  not  directly  productive  in  ordi- 
nary farm  products. 

The  areas  required  to  be  taken  from  the  forests 
for  agricultural  purposes  necessarily  greatly  ex- 
ceed those  required  for  the  location  of  ordinary 
roads  or  railroads.  The  damage  done  indirectly 
to  the  forest,  however,  by  the  location  of  new 
roads,  especially  railroads,  is  often  greater  than  by 
the  location  of  new  farming-lands,  since  the  loca- 
tion of  new  roads  greatly  increases  the  liability  to 
destructive  fires,  and  also  opens  up  extensive  tracts 
of  yet  unmolested  forest  to  the  greed  of  the  lum- 
berman, or  to  the  indifference  of  the  railroad 
authorities  or  of  the  travelling  public. 

Besides  this,  an  area  taken  for  agricultural  pur- 
poses is,  to  a  certain  extent,  protected  from  the 
loss  of  its  soil  by  a  covering  of  vegetation.  Dur- 
ing the  construction  and  operation  of  a  road-bed, 
much  of  the  adjoining  land  is  often  needlessly 
destroyed  by  being  thoughtlessly  left  for  floods 


FORESTRY.  13 

to  work  irreparable   damage  by  the  removal  of 
the  soil. 

It  is  for  the  purpose  of  regulating  the  necessary 
removal  of  the  forest,  and  for  pointing  out  the 
manner  in  which  the  products  of  the  forest  can 
be  most  advantageously  harvested,  that  Forestry 
Associations  and  Forestry  Laws  are  so  imperatively 
demanded. 

In  order  to  intelligently  protect  forest  areas, 
and  thus  aid  rather  than  oppose  nature  in  main- 
taining them,  the  principles  underlying  the  growth 
of  trees,  the  conditions  of  heat,  light,  and  moisture, 
or,  in  general,  the  conditions  of  climate  best  suited 
to  continue  such  growth,  must  be  carefully  studied. 
The  natural  influences  or  conditions  which  oppose 
the  growth  of  trees  must  be  ascertained,  and, 
where  possible,  checked ;  the  enemies  of  the  forest 
recognized,  and  the  best  means  taken  to  hold  them 
in  check.  In  other  words,  forestry  must  assume  the 
position  of  an  exact  science,  in  order  to  call  intelli- 
gently for  the  passage  of  laws  intended  for  insuring 
the  growth  and  reproduction  of  the  earth's  forests. 

It  is  a  mistaken  idea  that  forestry  endeavors  to 
preserve  intact  the   virgin   forests  of   the   earth. 
This  is  by  no  means  the  intent  of  intelligent  for- 
estry. 
>  2 


14  OUTLINES  OF  FORESTRY. 

The  wood  and  other  products  of  the  forest 
form  an  important  part  of  the  resources  of  a 
country.  Man  is  as  much  entitled  to  the  harvests 
of  the  woods  as  to  the  harvests  of  the  fields. 
Forestry  endeavors  to  point  out  the  best  ways  in 
which  forest  crops  may  be  harvested  without  detri- 
ment to  the  subsequent  crops,  and  without  causing 
the  ultimate  destruction  of  the  forest. 

Since  it  is  manifestly  impossible  to  preserve 
forests  on  all  parts  of  the  earth's  surface  where 
forests  can  naturally  grow,  it  should  be  the  duty 
and  care  of  every  community  to  set  aside  certain 
portions  where  forests  shall  be  perpetually  main- 
tained ;  or,  if  already  deforested,  shall  be  replanted 
or  reforested.  Such  preserves  were  originally 
maintained  by  the  arbitrary  will  of  the  sovereign 
lord  of  the  country,  for  the  good  of  a  few,  in 
order  to  insure  royal  hunting-grounds.  They 
should  now  be  maintained,  by  the  will  of  the 
people,  for  the  good  of  the  many. 

The  parts  best  suited  for  the  perpetual  mainte- 
nance of  forests  will  necessarily  vary  in  different 
regions. 

In  agricultural  districts,  certain  areas  should 
invariably  be  set  aside  on  which  trees  shall  be 
perpetually  preserved;  for  true  economy  requires 


FORESTRY.  15 

the  maintenance  of  some  timber  on  nearly  all 
farm-land. 

These  areas  will,  perhaps,  in  the  majority  of 
cases  be  found  as  follows, — viz. : 

1.  On  poor  or  thin  soils  where  no  other  crops 
will  thrive. 

2. -In  damp  places  where  no  other  crops  will 
thrive. 

3.  On  the  borders  of  rivers  or  other  streams. 

4.  On    mountain     slopes,    hill-tops,    or    other 
elevations. 

It  can  be  shown,  generally,  that  the  areas  which 
can  be  most  profitably  set  aside  for  the  mainte- 
nance of  perpetual  forests  are  situated,  for  the 
greater  part,  in  the  mountainous  districts  of  the 
earth,  the  natural  home  of  the  forest. 

As  will  hereafter  be  shown,  the  forests  should 
especially  be  preserved  on  mountain  slopes,  for  the 
following  reasons  : 

1.  Because  the  rain  falls  more  frequently  and 
in  greater  quantity  in  the  mountainous  districts 
of  the  earth  than  elsewhere.     The  cold  mountain 
slopes,  chilling  the  air,  cause  it  to  deposit  its  sur- 
plus moisture,  in  no  matter  from  what  direction 
the  winds  may  come. 

2.  Because  the  principal   rivers  of    the   earth 


16  OUTLINES  OF  FORESTRY. 

are  born  in  the  mountainous  districts,  and,  if  the 
forests  are  removed,  the  rain  which  falls  drains  so 
rapidly  from  the  earth's  surface  that  the  soil 
that  took  a  long  time  to  form  by  the  gradual 
disintegration  of  the  igneous  rocks,  and  slowly 
accumulated  its  vegetable  mould  from  the  growth 
and  subsequent  decay  of  thousands  of  generations 
of  plants,  is  lost  to  the  highlands,  only  to  become 
a  source  of  damage  to  the  lowlands. 

3.  Because  the  rapid  drainage  of  the  mountain 
slopes  on  the  removal  of  their  forests  will  result  in 
dangerous  floods  during  times  of  rain. 

4.  Because   the   failure  of  so  great  a  part  of 
the  rain-water  to  sink  into  the  ground  and  fill  the 
reservoirs  of  the  springs  will  cause  such  springs 
to  more  readily  dry  up  shortly  after  the  appear- 
ance of  drought. 

5.  Because    the    mountain    slopes,    when    de- 
prived of  their    forests,  become    excessively  hot 
during  the  day,  and  excessively  cold  during  the 
night,  and  thus  tend  to  sensibly  alter  the  climate 
of  the  country. 

6.  Because    such    marked    differences   in  tem- 
perature tend  to  increase  the  number  and  severity 
of  destructive  hail-storms. 

7.  Because  the  removal  of  the  forests  tends  to 


FORESTRY.  17 

increase  the  liability  of  occurrence  of  early  frosts 
in  the  neighboring  agricultural  districts. 

8.  Because  the  removal  of  the  forests  will  be 
attended  by  marked  changes  in  the  relative  quan- 
tity of  moisture  in  the  air  at  different  times  of  the 
year. 

B.  E.  Fernow,  Chief  of  the  Department  of  For- 
estry in  the  United  States  Department  of  Agricul- 
ture, in  a  paper  entitled  "  What  is  Forestry  ?"  * 
says,  on  page  15  : 

"  Forestry  in  a  wooded  country  means  harvesting  the  wood 
crop  in  such  a  manner  that  the  forest  will  produce  itself  in 
the  same,  if  not  in  superior,  composition  of  kinds.  Keproduc- 
tion,  then,  is  the  aim  of  the  forest  manager,  and  the  difference 
between  the  work  of  the  lumberman  and  that  of  the  forester 
consists  mainly  in  this :  that  the  forester  cuts  his  trees  with  a 
view  of  securing  valuable  reproduction,  while  the  lumber- 
man cuts  without  this  view,  or  at  least  without  the  knowledge 
as  to  how  this  reproduction  can  be  secured  and  directed  at 
will.  The  efficient  forest  manager  requires  no  tool  other  than 
the  axe  and  the  saw, — the  planing-tools  being  only  needed  to 
correct  his  mistakes, — but  he  sees  them  differently  from  the 
lumberman." 


*  Eeprinted,  by  permission,  from  "  What  is  Forestry  ?"  by 
B.  E.  Fernow,  Washington,  Government  Printing- Office,  1891. 
b  2* 


18  OUTLINES  OF  FORESTRY. 

The  true  position  which  forestry  takes  in  the 
United  States  is  thus  forcibly  expressed  in  the 
Annual  Report  of  the  New  York  Forest  Commis- 
sion, for  the  year  ending  December  31,  1890,*  on 
page  91,  as  follows  : 

"A  misunderstanding  has  prevailed  to  some  extent  with 
regard  to  the  attitude  of  forestry  towards  the  lumber  interests 
of  private  owners.  It  is,  however,  generally  misunderstood, 
now,  that  the  true  interests  of  the  lumbermen  are  not  incom- 
patible with  forest  preservation,  and  it  has  been  declared  to 
be  one  of  the  objects  of  the  forestry  movement  in  this  country 
'To  harmonize  the  interests  of  the  lumberman  and  the  for- 
ester, and  to  devise  for  the  lumbering  interest  such  protection 
as  is  not  given  at  the  cost  of  the  forests/  Forestry  is  not 
opposed  to  having  trees  cut  down  in  the  proper  way.  They 
must  be  cut  to  supply  the  world  with  timber.  They  furnish 
the  material  for  shelter  to  mankind,  and  contribute  to  render 
the  houses  of  men  comfortable  and  beautiful  by  providing 
fiiel  and  decorations.  It  is  needless  to  point  out  here  the 
manifold  purposes  for  which  wood  is  needed,  and  how  largely 
it  enters  into  our  industries  and  arts,  contributes  to  our  con- 
venience and  pleasure,  and  becomes  a  necessity  of  our  daily 
lives.  Civilization  could  hardly  exist  without  it.  It  is  from 
trees,  and  from  trees  only,  that  our  needs  for  wood  are  supplied 

*  Eeprinted,  by  permission,  from  Annual  Eeport  of  the 
New  York  Forest  Commission,  for  the  year  ending  Decem- 
ber 31,  1890.  Albany :  James  B.  Lyon,  State  Printer,  1891, 
Pp.  317. 


FORESTRY.  19 

through  the  timber-dealer  and  lumberman.  It  is  not  the  ex- 
ercise of  their  vocation,  but  their  frequent  abuse  of  it,  that 
calls  for  criticism, — a  distinction  that  has  not  always  been 
made  by  the  critics.  Estimates  show  that  thirty  billion  feet 
are  required  annually  in  this  country  for  building  and  manu- 
facturing purposes  alone,  leaving  the  fuel  question  out  of  con- 
sideration. It  is  the  unwise,  improvident,  stupid  method,  or 
want  of  method,  by  which  the  cutting  has  heretofore  too  often 
been  done,  that  is  deplored.  Under  the  old  practice  the 
forests  have  rapidly  disappeared,  and,  if  it  continues,  in  a  few 
years  none  will  be  left.  The  lumberman  will  have  ruined  his 
own  business,  as  there  will  be  no  forests  to  furnish  him  with 
his  stock  in  trade.  It  is  the  purpose  of  forestry  to  point  out 
to  the  lumberman  the  true  methods  of  exercising  his  own 
profession,  which  will  provide  him  material  for  the  future,  as 
well  as  the  present,  by  maintaining  permanent  forests  through 
a  succession  of  crops." 


20  OUTLINES  OF  FORESTRY. 


II.    CONDITIONS  NECESSARY  FOR  THE 
GROWTH   OF   PLANTS. 

EXTENDED  scientific  research  has  established  the 
fact  that  all  forms  of  life,  whether  of  the  animal 
or  the  plant,  can,  at  their  earliest  stages,  be  traced 
to  a  minute  germ-cell  filled  with  a  more  or  less 
transparent  substance  called  protoplasm,  and  con- 
taining a  dark,  opaque  spot  called  the  nucleus. 
Unless  this  germ-cell  exists,  plant  or  animal  life  is 
impossible. 

Although  cases  exist  where  there  has  been  no 
apparent  evidence  of  the  presence  of  a  germ  or 
seed,  yet  such  germ  or  seed  must  have  existed, 
and  was  derived  from  a  plant  of  exactly  the  same 
character  as  that  which  such  seed  will  produce 
when  called  into  active  and  matured  growth. 

Under  peculiar  circumstances,  plant  or  animal 
germs  possess  wonderful  vitality,  and  may  remain 
in  a  dormant  state  for  a  very  long  time,  only 
beginning  to  grow  when  exposed  to  the  conditions 
necessary  for  growth. 

In  order  that  any  form  of  plant  life  may  exist 


CONDITIONS  FOR   THE  GROWTH  OF  PLANTS.      21 

on  the  earth,  the  following  conditions  are  neces- 
sary : 

1.  The    germ  or   seed    from  which  the  plant 
grows. 

The  germ  or  seed  in  all  cases  comes  directly 
from  a  plant  similar  to  that  which  is  produced 
when  the  seed  sprouts  or  germinates,  and  attains 
its  full  growth. 

2.  The  cradle  where  the  plant  is  born. 

The  plant's  cradle  is  the  soil.  In  the  soil  the 
plant  spreads  its  roots,  and  from  it  obtains,  in 
great  part,  the  materials  necessary  for  nourish- 
ment and  growth. 

Cases  exist  where  the  plant  finds  its  cradle  in 
the  air  or  in  the  water.  These  need  not,  however, 
be  considered  in  this  connection. 

3.  The  sunshine  and  the  heatshine,  which  awaken 
the  sleeping  germ  and  call  it  into  activity ;  or,  in 
other  words,   the  light  and  heat  which   are   so 
essential  to  a  plant's  growth. 

4.  The    nourishment,   or    the   food  which  the 
plant  takes  into  its  structure  and  assimilates,  and 
thus  causes  it  to  become  a  part  of  itself. 

The  processes  by  which  a  plant  causes  different 
materials  taken  from  the  soil  in  which  it  grows, 
or  from  the  air  around  it,  to  become  a  part  of 


22  OUTLINES  OF  FORESTRY 

itself,  is  called  assimilation.  At  the  commence- 
ment of  its  life  the  plant  gets  its  nourishment 
from  the  protoplasm  surrounding  the  nucleus.  It 
is  not  long,  however,  before  it  exhausts  this  stock 
of  food,  and  it  must  then  get  all  its  nourishment 
either  from  the  soil  or  from  the  atmosphere ;  or, 
in  other  words,  from  outside  the  seed. 

This  latter  nourishment  of  the  plant  comes 
from  a  variety  of  materials,  derived  either  from 
the  air  or  from  the  ground,  the  most  important 
of  which  are  as  follows  : 

1.  Moisture. 

This  moisture  is  mainly  taken  up  by  the  roots 
of  the  plant  from  the  soil;  but  it  is,  in  some 
cases,  absorbed  directly  from  the  air  by  the  leaves. 

2.  Carbonic  acid. 

Carbonic  acid  is  a  gaseous  substance,  formed  of 
carbon  combined  with  an  invisible  gas  called  oxy- 
gen. The  carbonic  acid  is  absorbed  by  the  leaves 
of  the  plant,  and,  in  the  presence  of  sunshine,  is 
broken  up  into  carbon  and  oxygen.  The  oxygen 
is  given  oft*  from  the  surfaces  of  the  leaves,  and 
the  carbon  is  retained  by  the  plant  to  form  its 
woody  fibre.  In  the  case  of  large  vegetable  forms 
like  forest-trees,  the  amount  of  carbonic  acid  taken 
from  the  air  and  converted  into  woody  fibre  must 


CONDITIONS  FOR   THE  GROWTH  OF  PLANTS.      23 

be  very  great.  A  certain  amount  of  oxygen,  how- 
ever, must  be  present  in  the  air,  to  permit  the 
continued  growth  of  the  plant ;  for  most  plants  will 
not  grow  in  an  atmosphere  of  pure  carbonic  acid  gas. 

The  hydrogen  needed  for  the  plant's  growth  is 
derived  from  the  decomposition  of  the  water  asso- 
ciated with  the  carbonic  acid;  the  result  is  that 
the  plant  retains  the  carbon  and  the  hydrogen,  and 
throws  out  the  oxygen  into  the  atmosphere. 

3.  Mineral  matters  taken  from  the  soil. 

The  tissues  of  the  plant  contain  various  kinds 
of  mineral  substances  which  are  taken  directly 
from  the  soil.  For  the  proper  growth  of  the 
plant,  the  soil  must  contain  these  particular  min- 
eral substances  in  the  condition  or  state  in  which 
they  can  be  readily  taken  up  or  assimilated  by  the 
plant. 

The  above  conditions — viz.,  the  germ,  the  cradle, 
the  sun's  light  and  heat,  and  some  form  of  solid 
and  liquid  food — are  not  of  equal  importance  to 
the  growth  of  the  plant. 

The  presence  of  the  germ  or  seed  is,  of  course, 
of  the  greatest  importance,  since  without  it  no 
plant  can  grow. 

The  sunshine  and  the  heat  may,  perhaps,  be 
considered  as  next  in  importance  to  the  growth 


24  OUTLINES  OF  FORESTRY. 

of  the  plant.  Heat  and  light  are  to  be  found  in 
practically  all  parts  of  the  earth.  They  differ, 
however,  in  amount,  in  different  regions  of  the 
earth,  and  such  differences  cause  the  differences 
that  are  noticed  in  the  plants  that  grow  in  dif- 
ferent regions. 

Even  in  the  same  region,  differences  in  the  light 
and  heat  cause  differences  in  the  plant's  growth, 
as  may  be  noticed  in  almost  any  forest  region. 

The  plants  that  form  the  undergrowth  of  those 
portions  of  the  forest  where  the  light  is  more 
thoroughly  shut  out  are  markedly  different  from 
those  appearing  in  the  clearings,  where  the  light 
and  heat  have  full  access  to  the  soil. 

The  nourishment  of  the  plant  comes  next  in 
importance.  The  quantity  of  carbonic  acid  found 
in  the  air  is  practically  the  same  in  all  parts  of  the 
earth.  The  quantity  of  moisture  in  the  air  differs 
very  greatly  in  different  parts  of  the  earth,  and 
on  this  difference,  together  with  the  difference  of 
temperature,  depends  the  differences  observed  in 
the  plants  of  various  regions. 

The  liquid  nourishment  of  the  plant  in  the 
shape  of  water  is  of  so  great  importance  to  the 
growth  of  the  plant,  that  the  character  of  the 
rain-fall  in  any  country  will,  to  a  marked  ex- 


CONDITIONS  FOR   THE  GROWTH  OF  PLANTS.      25 

tent,  determine  the  character  of  the  flora  of  that 
country. 

The  soil  is,  perhaps,  the  least  important  of  the 
conditions  required  for  plant  growth. 

This  statement  is  at  first  thought  so  much  at 
variance  with  the  generally  received  opinion  as  to 
need  an  explanation. 

"Where  a  particular  kind  of  plant  is  to  be  grown, 
the  character  of  the  soil,  probably,  stands  next  in 
importance  to  the  presence  of  the  germ  or  seed ; 
for  each  plant  thrives  best  in  a  particular  kind  of 
soil.  The  variety  of  plants  that  exist,  however, 
is  so  great  that,  given  almost  any  kind  of  soil, 
together  with  certain  conditions  of  heat,  light, 
and  moisture,  such  soil  will  be  found  to  be  best 
suited  for  the  growth  of  some  particular  kind  of 
plant.  In  other  words,  if  the  proper  conditions 
of  moisture,  heat,  and  light  are  present,  and  the 
germ  is  present,  vegetation  will  appear  in  almost 
any  region. 

Nature  has  generously  scattered  the  germs  of 
various  forms  of  plant  life  nearly  all  over  the 
earth's  surface.  Therefore,  if  unmolested  by  man, 
she  will,  in  most  cases,  maintain  on  such  surfaces 
the  kind  of  plant  forms  or  plant  growths  best 
suited  to  grow  naturally. 


26  OUTLINES  OF  FORESTRY. 

There,  therefore,  will  be  found  in  every  section 
of  country  a  plant  growth  or  plant  life  peculiar 
to,  or  naturally  belonging  to,  such  a  section  of 
country.  Each  section  of  country  possesses,  so 
to  speak,  a  nationality  in  its  plants,  or,  in  other 
words,  there  lives  in  each  section  of  country  a 
particular  nation  of  plants.  Such  a  nation  of 
plants,  or  the  plants  peculiar  to  a  particular  sec- 
tion of  country,  is  called  its  flora. 

Since  heat,  light,  and  moisture  are,  next  to  the 
presence  of  the  plant  germ,  the  most  important 
things  for  plant  growth,  there  will  necessarily 
exist  in  different  parts  of  the  earth  a  flora  that  will 
vary  according  to  the  differences  that  exist  in  the, 
distribution  of  heat,  light,  and  moisture  over  such 
part  of  the  earth's  surface. 

The  heat,  light,  and  moisture  are  greater  in 
amount  at  the  equator  than  at  any  other  portion 
of  the  earth's  surface.  Therefore,  the  vegetation 
is  more  luxuriant,  or  possesses  a  greater  diversity 
of  forms,  here  than  at  any  other  part  of  the  sur- 
face. As  we  pass  from  the  equator  towards  the 
poles,  the  decrease  in  the  heat,  light,  and  moisture 
causes  a  corresponding  decrease  in  the  variety  and 
luxuriance  of  vegetable  life. 

In  passing  from  the  base  to  the  summit  of  a 


CONDITIONS  FOR   THE  GROWTH  OF  PLANTS.      27 

high  tropical  mountain,  the  same  differences  in 
the  variety  and  luxuriance  of  plant  life  are  noticed 
that  are  seen  in  going  from  the  equator  to  the 
poles.  This  is  due  mainly  to  the  distribution  of 
the  heat  and  moisture. 

The  planting  of  a  germ  or  seed  in  any  soil  will 
not  result  in  its  continued  growth,  unless  the  con- 
ditions of  heat,  light,  and  moisture  are  practically 
the  same  as  those  in  which  the  plant  from  which 
such  germ  or  seed  was  derived  required  for  its 
existence. 

Trees  planted  in  a  particular  locality  may,  there- 
fore, fail  to  grow  in  such  locality,  from  want  of 
the  proper  conditions  of  heat,  light,  and  moisture. 

In  all  regions  where  forests  can  grow  naturally, 
wherever  practicable,  they  should  be  permitted  to 
grow,  since,  as  will  be  shown,  the  continued  ex- 
istence of  forests  on  certain  portions  of  the  earth 
is  necessary  for  insuring  that  balance  of  nature  on 
which  the  comfortable  existence  of  man  depends. 

Guyot,  on  page  188  in  his  "  Earth  and  Man,"  * 

*  "  The  Earth  and  Man,"  lecture  on  Comparative  Physi- 
cal Geography  in  its  Relation  to  the  History  of  Mankind,  by 
Arnold  Guyot,  Professor  of  Physical  Geography  and  History 
at  Neufchatel,  Switzerland.  Boston :  Gould,  Kendall  &  Lin- 
coln, 1849. 


28  OUTLINES  OF  FORESTRY. 

thus  refers  to  the  conditions  favorable  to  luxuriant 
vegetable  growth : 

"The  warm  and  the  moist — these  are  the  most  favorable 
conditions  for  the  production  of  an  exuberant  vegetation. 
Now,  the  vegetable  covering  is  nowhere  so  general,  the  vege- 
tation so  predominant,  as  in  the  two  Americas.  Behold, 
under  the  same  parallel  where  Africa  presents  only  parched 
table-lands,  those  boundless  virgin  forests  of  the  basin  of  the 
Amazon,  those  selvas,  almost  unbroken  over  a  length  of  more 
than  fifteen  hundred  miles,  forming  the  most  gigantic  wilder- 
ness of  this  kind  that  exists  in  any  continent.  And  what 
vigor,  what  luxuriance  of  vegetation !  The  palm-trees,  with 
their  slender  forms,  calling  to  mind  that  of  America  itself, 
boldly  uplifted  their  heads  one  hundred  and  fifty  or  two  hun- 
dred feet  above  the  ground,  and  domineer  over  all  the  other 
trees  of  these  wilds,  by  their  height,  by  their  number,  and  by 
the  majesty  of  their  foliage.  Innumerable  shrubs  and  trees 
of  smaller  height  fill  up  the  space  that  separates  their  trunks  ; 
climbing  plants,  woody- stemmed,  twining  lianos,  infinitely 
varied,  surround  them  both  with  their  flexible  branches,  dis- 
play their  own  flowers  upon  the  foliage,  and  combine  them  in 
a  solid  mass  of  vegetation,  impenetrable  to  man,  which  the 
axe  alone  can  break  through  with  success.  On  the  bosom  of 
their  peaceful  waters  swims  the  Victoria,  the  elegant  rival  of 
the  Rafllesia,  that  odorous  and  gigantic  water-lily,  whose  white 
and  rosy  corolla,  fifteen  inches  in  diameter,  rises  with  a  daz- 
zling brilliancy  from  the  midst  of  a  train  of  immense  leaves, 
softly  spread  upon  the  waves,  a  single  one  covering  a  space  of 
six  feet  in  width.  The  rivers,  rolling  their  tranquil  waters 


CONDITIONS  FOR   THE  GROWTH  OF  PLANTS.      29 

under  verdurous  domes,  in  the  bosom  of  these  vast  wilds,  are 
the  only  paths  that  nature  has  opened  to  the  scattered  inhabi- 
tants of  these  rich  solitudes.  Elsewhere,  in  Mexico  and  Yu- 
catan, an  invading  vegetation  permits  not  even  the  works  of 
man  to  exist ;  and  the  monuments  of  a  civilization  compara- 
tively ancient,  which  the  antiquary  goes  to  investigate  with 
care,  are  soon  changed  into  a  mountain  of  verdure,  or  demol- 
ished, stone  after  stone,  by  the  plants  piercing  into  their 
chinks,  pushing  aside  with  vigor,  and  breaking  with  irresisti- 
ble force,  all  the  obstacles  that  oppose  their  rapid  growth." 

The  author,  in  his  "  Elements  of  Physical  Geog- 
raphy," *  page  119,  thus  refers  to  the  growth  of 
living  matter : 

"  All  life,  whether  vegetable  or  animal,  consists  of  various 
groupings  of  cells,  or  approximately  spherical  masses,  con- 
sisting of  a  peculiar  form  of  a  jelly-like  matter  called  proto- 
plasm, composed  of  various  complex  combinations  of  carbon, 
hydrogen,  oxygen,  and  sulphur,  called  proteids.  At  its  begin- 
ning all  life  consists  of  a  minute  germ-cell,  filled  with  more 
or  less  transparent  protoplasm,  and  containing  a  darker 
opaque  spot  called  the  nucleus.  Examined  by  a  sufficiently 
powerful  glass,  all  living  protoplasm  is  seen  to  be  in  constant 
motion,  currents  passing  through  the  different  parts  in  some- 
what definite  directions. 

*  Eeprinted,  by  permission,  from  "  The  Elements  of  Physical 
Geography,  for  the  Use  of  Schools,  Academies,  and  Colleges." 
By  Edwin  J.  Houston,  A.M.  Eldredge  &  Brother,  No.  17 
North  Seventh  Street,  Philadelphia.  1891.  Pp.  272. 

3* 


30  OUTLINES  OF  FORESTRY. 

"  As  the  germ-cell  develops  in  all  the  higher  forms  of  life,  it 
multiplies,  and  various  organs  appear,  peculiar  to  the  form  of 
life  from  which  the  germ-cell  was  derived.  All  living  bodies 
contain  organs,  and  living  matter  is  therefore  sometimes  called 
organic  matter,  to  distinguish  it  from  non-living  or  inorganic 
matter. 

"Science  has  not  yet  disclosed  the  nature  of  the  change 
whereby  non-living  matter  is  converted  into  living  protoplasm. 
To  produce  living  matter,  the  intervention  of  already  living 
matter  is,  so  far  as  is  known,  absolutely  necessary." 

Concerning  the  influence  of  climate  on  plant 
growth,  ]£lisee  Reclus,  in  his  work, "  The  Ocean,"* 
on  page  361,  says : 

"  Each  plant  has  its  special  domain,  determined  not  only 
by  the  nature  of  the  soil,  but  also  by  the  various  conditions 
of  climate,  temperature,  light,  moisture,  the  direction  and 
force  of  winds,  and  of  oceanic  currents.  During  the  course 
of  ages  the  extent  of  this  domain  changes  incessantly,  accord- 
ing to  the  modifications  which  are  produced  in  the  world  of 
air,  and  the  limits  of  the  region  inhabited  by  the  various 
species  are  dovetailed  into  one  another  in  the  most  compli- 
cated manner.  The  flora  indicates  the  climate ;  but  what  is 
the  climate  itself,  in  the  apparently  confused  mixture  of 
phenomena  which  compose  it  ?  The  preponderating  influence 

*  Eeprinted,  by  permission,  from  "  The  Ocean,  Atmosphere, 
and  Life,"  by  ElisSe  Eeclus.  New  York :  Harper  &  Brothers, 
Publishers,  Franklin  Square.  1874.  Pp.  534. 


CONDITIONS  FOR   THE  GROWTH  OF  PLANTS.      31 

is  naturally  that  of  temperature ;  nevertheless,  we  must  not 
think,  as  many  botanists  did  till  very  recently,  that  the  limits 
of  the  zone  of  vegetation  of  each  plant  are  marked  on  the 
continents  by  the  insinuosities  of  the  isothermal  lines.  In  fact, 
as  Charles  Martins  and  Alphonse  de  Candolle  remark,  each 
plant  requires  for  its  germination  and  development  a  certain 
amount  of  temperature,  differing  according  to  the  species. 
With  some,  life  resumes  its  activity  after  the  sleep  of  winter, 
when  the  thermometer  marks  three  or  five  degrees  above  the 
freezing-point ;  others  need  a  heat  of  eighteen,  twenty,  and 
even  twenty-five  and  thirty-five  degrees,  before  taking  the  first 
step  in  their  career  of  the  year.  Each  species  has,  so  to  say, 
its  particular  thermometer,  the  zero  of  which  corresponds  to 
the  degrees  of  temperature  when  the  vegetating  force  awakens 
its  germs.  It  is,  therefore,  impossible  to  indicate  by  such 
general  climatal  lines  the  limits  of  habitation  for  such  or  such 
species,  since  each  one  of  them  has  for  the  commencement  of 
its  vital  period  a  different  starting-point." 


32  OUTLINES  OF  FORESTRY. 


III.    THE    WIDE     DISTRIBUTION     OF 
PLANT   GERMS. 

IN  order  that  seed-time  and  harvest  shall  not 
fail  on  the  earth,  nature  has  distributed  the  seeds 
or  germs  of  plant  life  with  a  liberal  hand  over 
all  parts  of  the  surface.  Even  amid  the  burning 
sands  of  the  deserts  and  the  eternal  snows  of  the 
polar  regions,  myriad  forms  of  plant  germs  exist. 

Nature  has  provided  numerous  ways  for  insuring 
the  thorough  scattering  of  these  plant  germs  or 
seeds. 

Many  forms  of  seeds  are  provided  with  delicate 
hair-like  projections,  or  with  wings,  by  means  of 
which  they  are  carried  by  the  winds  to  great 
distances.  Others  are  provided  with  projecting 
hooks  or  bristles,  by  means  of  which  they  catch 
in  the  fur  of  animals,  or  in  the  plumage  of  birds, 
and  are  thus  carried  into  distant  regions. 

Perhaps  one  of  the  most  important  of  the 
means  provided  by  nature  for  the  distribution  of 
plant  germs,  is  that  the  seeds,  which  are  swallowed 
whole  by  birds  or  other  animals,  subsequently  pass 


THE   WIDE  DISTRIBUTION  OF  PLANT-GERMS.      33 

out  of  the  animal  uninjured  by  the  process  of 
digestion.  By  such  means  seeds  are  carried  to 
distant  parts  of  the  earth. 

Man,  either  purposely  or  accidentally,  scatters 
plants,  germs,  or  seeds  in  far-distant  countries. 
Not  unfrequently  some  of  the  plants  thus  brought 
from  one  country  to  another  find  the  conditions 
of  soil  and  climate  in  their  new  home  so  favorable 
to  growth  as  to  completely  drive  out  and  exter- 
minate domestic  species. 

Besides  the  means  just  mentioned  for  the  scatter- 
ing of  germs  or  seeds  of  plants,  there  are  possibly 
others  that  have  not  yet  been  recognized. 

The  germs  or  seeds  of  plants  possess  a  singular 
vitality  under  certain  conditions.  The  grains  of 
corn  or  wheat  found  in  the  Egyptian  mummies,  in 
many  cases,  grew  and  bore  fruit  notwithstanding 
their  centuries  of  rest.  Such  instances  of  the 
preservation  of  vitality  are,  perhaps,  less  wonder- 
ful when  viewed  in  the  light  of  the  exceedingly 
dry  climate  in  which  the  mummies  were  preserved. 
More  curious  instances  are  found  in  which  the 
germs  existed  for  a  long  time  in  the  presence  of 
an  abundance  of  moisture,  and  did  not  grow  as 
long  as  the  heat  and  light  alone  were  absent. 

The  truth  of  the  above  statements  is  denied  by 


34  OUTLINES  OF  FORESTRY. 

some,  but  that    such    experiments  succeeded  in 
some  cases  is  undoubtedly  true. 

For  example,  in  densely-wooded  countries,  where 
the  ground  is  thickly  covered  with  trees,  the  light 
and  heat  of  the  sun  are  so  thoroughly  expended 
in  maintaining  such  growth  that  no  other  forms 
of  plant  life  occur.  Let,  however,  some  of  the 
trees  be  removed,  so  that  the  light  and  heat  of 
the  sun  may  reach  the  ground,  and  the  seeds  that 
were  there,  possibly  during  the  centuries  that  the 
forest  covered  it,  at  once  spring  into  active  life. 
Here  all  the  conditions  except  sufficient  light  and 
heat  were  present,  and  yet  the  germs  slumbered. 

That  the  Sahara  desert  was  once,  in  certain 
portions,  if  not  in  all  parts,  well  watered,  is 
attested  by  the  presence  of  the  wadys,  or  deserted 
river-valleys.  That  the  soil  of  the  desert  contains 
a  liberal  supply  of  numerous  plant  germs,  is  shown 
by  the  fact  that,  on  the  successful  sinking  of  an 
artesian  well,  the  appearance  of  the  water  is  in- 
variably attended  by  the  appearance  of  a  flora 
often  containing  peculiar  species  of  plants.  Here 
the  light,  heat,  and  soil  were  all  present,  and  yet 
the  germs  slumbered  for  want  of  moisture. 

The  boring  of  artesian  springs,  or  the  digging 
of  cellars  or  other  excavations,  by  bringing  to  the 


THE   WIDE  DISTRIBUTION  OF  PLANT-GERMS.      35 

sun's  light  and  heat  soil  which  has  been  deprived 
of  such  sunlight  and  heat  for  unknown  ages,  in 
many — indeed,  in  most — cases  is  followed  by  the 
appearance  of  vegetation  often  containing  species 
quite  strange  to  that  particular  section  of  country. 

A  curious  story  of  such  a  case  is  told,  which,  if 
true,  shows  in  a  striking  manner  the  wonderful 
vitality  of  certain  seeds.  In  a  given  section  of 
country,  let  us  say  in  England,  a  farmer  com- 
menced to  dig  a  well.  This  act,  so  common  in 
an  agricultural  district,  attracted  no  particular 
attention  until  the  depth  of  the  still  dry  hole  far 
exceeded  that  of  most  wells  in  the  locality.  The 
neighbors  then  began  to  speculate  as  to  whether 
the  farmer  would  eventually  strike  water,  but 
when  he  continued  without  success,  many  of  his 
neighbors  began  to  quietly  laugh  at  him.  The 
farmer,  however,  persisted,  and  at  last  his  per- 
sistency or  stubbornness,  whichever  it  may  have 
been,  was  rewarded. 

After  having  dug  through  a  considerable  deposit 
of  sand,  which  appeared  very  much  like  the  sand 
of  an  ancient  sea-beach,  a  water-logged  stratum 
was  reached  from  which  gushed  forth  a  copious 
supply  of  excellent  water.  So  pleased  was  the 
farmer  with  the  result  of  his  labors,  that  he  ar- 


36  OUTLINES  OF  FORESTRY. 

ranged  the  sand  and  other  materials  brought  up 
from  below  in  a  form  of  a  garden-plot  around  the 
mouth  of  the  well.  Strange  plants  soon  appeared, 
and  among  them  a  tree,  which,  when  sufficiently 
matured,  proved  to  be  an  ancient  form  of  beech- 
plum.  Now,  since  it  is  universally  recognized  that 
no  form  of  plant  life  appears  without  the  presence 
of  a  germ  similar  to  that  which  the  plant  will  it- 
self produce,  the  germ  of  this  ancient  beech-plum 
was  presumably  preserved  in  the  deep-seated  strata 
for  untold  centuries,  awaiting  to  be  called  into  life 
by  the  genial  warmth  and  light  of  the  sun. 

The  virgin  soil  of  the  prairies,  where  turned  up 
by  the  plough  of  the  settler,  generally  produces  a 
vegetation  different  from  that  of  the  undisturbed 
eoil.  Even  the  tracks  of  the  settlers'  wagons  dis- 
turb the  soil  sufficiently  to  be  afterwards  marked 
by  a  growth  of  plants  quite  distinct  from  those 
which  cover  the  undisturbed  portions.  The  seeds 
must  have  lain  a  long  time  below  the  surface, 
only  springing  into  active  life  on  exposure  to  the 
light  and  heat  of  the  sun. 

The  burning  of  a  pine  forest  in  the  North  Tem- 
perate Zone  is  almost  invariably  followed  by  a 
growth  of  scrub  oak.  "What  was  the  origin  of 
the  germs  of  these  oaks  ?  They  presumably  ex- 


THE    WIDE  DISTRIBUTION  OF  PLANT-GERMS.      37 

isted  in  the  ground,  and,  in  some  as  yet  unex- 
plained manner,  were  aroused  into  active  life  by 
the  presence  of  the  fire. 

In  some  parts  of  the  United  States  the  burning 
over  of  a  region  is  almost  invariably  followed  by 
a  growth  of  what  is  very  appropriately  called  fire- 
weed,  the  seeds  of  which  appear  to  have  been 
called  into  active  life  in  some  as  yet  unexplained 
manner,  either  by  something  added  to  the  soil  by 
the  heat,  or  possibly  by  the  heat  of  the  fire  itself. 

Cases  are  on  record  where  earthquakes  have 
brought  up  to  the  surface,  soil  which  had  probably 
been  buried  for  ages,  but  which,  on  exposure  to 
the  light  and  heat  of  the  sun,  gave  birth  to  strange 
forms  of  plant  life. 

Possibly,  in  some  of  the  cases  mentioned,  the 
germs  of  plant  life  have  been  carried  to  the  locali- 
ties by  one  or  another  of  the  agencies  already 
mentioned.  In  other  cases,  however,  the  germs 
appear  to  have  existed  in  the  soil,  waiting  to  be 
called  into  life  by  the  sun's  light  and  heat. 

Nature,  therefore,  has  taken  care  that  the  earth 
shall  be  covered  with  a  vegetable  carpet  wherever 
man  does  not  oppose  her  action.  If  left  to  work 
out  her  own  course,  she  will  cover  the  earth  with 
a  dress  of  such  vegetable  forms  as  are  best  suited 

4 


38  OUTLINES  OF  FORESTRY. 

to  exist  there  naturally.  If  interfered  with,  to 
even  a  comparatively  trifling  degree,  such  changes 
may  be  produced  in  the  soil,  climate,  or  other 
conditions  as  will  bring  wide-spread  destruction 
to  widely  separated  sections  of  the  country. 

Speaking  of  the  vitality  of  seeds,  Marsh,  in  his 
work  entitled  "  The  Earth  as  Modified  by  Human 
Action,"  *  page  295,  says : 

"  When  newly-cleared  ground  is  burnt  over  in  the  United 
States,  the  ashes  are  hardly  cold  before  they  are  covered  with 
a  crop  of  fire-weed,  Senecio  hieracifolius,  a  tall,  herbaceous 
plant,  very  seldom  seen  growing  under  other  circumstances, 
and  often  not  to  be  found  for  a  distance  of  many  miles  from 
the  clearing.  Its  seeds,  whether  the  fruit  of  an  ancient  vegeta- 
tion or  newly  sown  by  winds  or  birds,  require  either  a  quicken- 
ing by  a  heat  which  raises  to  a  high  point  the  temperature  of 
the  stratum  where  they  lie  buried,  or  a  special  pabulum  fur- 
nished only  by  the  combustion  of  the  vegetable  remains  that 
cover  the  ground  in  the  woods. 

"Earth  brought  up  from  wells  or  other  excavations  soon 
produces  a  harvest  of  plants  often  very  unlike  those  of  local 
flora,  and  Hay  den  informs  us  that  on  our  great  Western  desert 
plains,  wherever  the  earth  is  broken  up,  the  wild  sunflower 
(Helianthus)  and  others  of  the  taller-growing  plants,  though 

*  Reprinted,  by  permission,  from  "  The  Earth  as  Modified  by 
Human  Action,"  by  George  P.  Marsh.  New  York :  Scribner, 
Armstrong  &  Co.,  No.  654  Broadway,  1874.  Pp.  656. 


THE   WIDE  DISTRIBUTION  OF  PLANT-GERMS.      39 

previously  unknown  in  the  vicinity,  at  once  spring  up,  almost 
as  if  spontaneous  generation  had  taken  place." 

The  wonderful  vitality  of  certain  seeds  is  thus 
referred  to  by  Lindley  in  his  "  Botany,"  *  on  page 
358: 

"  The  action  of  seeds  is  confined  to  that  phenomenon  which 
occurs  when  the  embryo  which  the  seed  contains  is  first  called 
into  life,  and  which  is  named  germination. 

"  If  seeds  are  sown  as  soon  as  they  are  gathered,  they  gener- 
ally vegetate,  at  the  latest,  in  the  ensuing  spring ;  but,  if  they 
are  dried  first,  it  often  happens  that  they  will  lie  a  whole  year 
or  more  in  the  ground  without  altering.  This  character  varies 
extremely  in  diiferent  species.  The  power  of  preserving  their 
vitality  is  also  variable :  some  will  retain  their  germinating 
powers  many  years,  in  any  latitude,  and  under  almost  any 
circumstances.  Melon-seeds  have  been  known  to  grow  when 
forty-one  years  old,  maize  thirty  years,  rye  forty  years,  the 
sensitive  plant  sixty  years,  kidney-beans  one  hundred  years. 
Clover  will  come  up  from  soil  newly  brought  to  the  surface  of 
the  earth,  in  places  in  which  no  clover  had  been  previously 
known  to  grow  in  the  memory  of  man,  and  I  have  at  this  mo- 
ment three  plants  of  raspberries  before  me,  which  have  been 
raised  in  the  garden  of  the  Horticultural  Society  from  seeds 
taken  from  the  stomach  of  a  man  whose  skeleton  was  found 

*  "  An  Introduction  to  Botany,"  by  John  Lindley,  Ph.D. 
London:  Longman,  Orme,  Brown,  Green,  and  Longmans. 
Third  Edition,  1839.  Pp.  594. 


40  OUTLINES  OF  FORESTRY. 

thirty  feet  below  the  surface  of  the  earth,  at  the  bottom  of  a 
barrow  which  was  opened  near  Dorchester.  He  had  been 
buried  with  some  coins  of  the  Emperor  Hadrian,  and  it  is 
therefore  probable  that  the  seeds  were  sixteen  or  seventeen 
hundred  years  old." 

"  It  has  already  been  seen  that  under  certain  circumstances, 
the  vitality  of  seeds  may  be  preserved  for  a  very  considerable 
length  of  time ;  but  it  is  difficult  to  say  what  are  the  exact 
conditions  under  which  this  is  effected.  We  learn  from  ex- 
periment that  seeds  will  not  germinate  if  placed  in  vacua,  or 
in  an  atmosphere  of  hydrogen,  nitrogen,  or  carbonic  acid ;  but 
no  such  conditions  exist  in  nature,  and,  therefore,  it  cannot 
be  they  which  have  occasionally  preserved  vegetable  vitality 
in  the  embryo  plant  for  many  years.  Perhaps  the  following 
remarks,  in  a  work  lately  published  by  the  Society  for  the 
Diffusion  of  Useful  Knowledge,  may  throw  some  light  on  the 
subject  : 

"  It  may,  upon  the  whole,  be  inferred  from  the  duration  of 
seeds  buried  in  the  earth,  and  from  other  circumstances  that 
the  principal  conditions  are,  1,  uniform  temperature ;  2,  mod- 
erate dryness ;  3,  exclusion  of  light ;  and  it  will  be  found 
that  the  success  with  which  seeds  are  transported  from  foreign 
countries,  in  a  living  state,  is  in  proportion  to  the  care  and 
skill  with  which  these  conditions  are  preserved.  For  exam- 
ple, seeds  brought  from  India,  round  the  Cape  of  Good  Hope, 
rarely  vegetate  freely :  in  this  case  the  double  exposure  to  the 
heat  of  the  equator,  and  the  subsequent  arrival  of  the  seeds 
in  cold  latitudes,  are  probably  the  causes  of  their  death ;  for 
seeds  brought  overland  from  India,  and  therefore  not  exposed 
to  such  fluctuations  of  temperature,  generally  succeed.  Others, 


THE   WIDE  DISTRIBUTION  OF  PLANT-GERMS.     41 

again,  which  cannot  be  conveyed  with  certainty  if  exposed  to 
the  air,  will  travel  in  safety  for  many  months  if  buried  in 
clay  rammed  hard  in  boxes :  in  this  manner  only  can  the 
seeds  of  the  mango  be  brought  alive  from  the  West  Indies  ; 
and  it  was  thus  the  principal  part  of  the  Araucania  pines,  now 
in  England,  were  transported  from  Chile.  It  may  therefore 
be  well  worth  consideration,  whether  by  some  artificial  con- 
trivance, in  which  these  principles  shall  be  kept  in  view,  it 
may  not  be  possible  to  reduce  to  something  like  certainty  the 
preservation  of  seeds  in  long  voyages, — such,  for  instance,  as 
by  surrounding  them  with  many  layers  of  non-conducting 
matter,  as  case  over  case  of  wood,  or  by  ramming  every  other 
space,  in  such  cases,  with  clay  in  a  dry  state." 


42  OUTLINES  OF  FORESTRY. 


IV.  CONDITIONS  NECESSARY  FOR  THE 
GROWTH  OF  TREES. 

IF  a  soil  exists  in  any  locality,  and  certain  con- 
ditions of  light,  heat,  and  moisture  are  present, 
the  character  of  the  vegetation  that  naturally 
grows  in  such  a  region  will  depend  more  on  the 
peculiarities  of  the  distribution  of  the  heat,  light, 
and  moisture,  than  on  the  character  of  the  soil 
itself. 

If  moisture  be  entirely  absent,  or  if  it  exists  in 
such  a  form  as  ice  or  snow,  in  which  it  cannot  be 
readily  appropriated  by  plants,  then  that  region 
must  become  a  desert. 

Deserts  occur  either  in  dry,  arid  regions,  or  in 
the  regions  of  perpetual  snow  of  the  polar  zones, 
or  on  the  higher  mountain  slopes. 

If  the  rainfall  is  absent  during  certain  seasons  of 
the  year,  but  occurs  during  the  rest  of  the  year, — 
that  is,  if  one  part  of  the  year  is  dry  and  the  rest 
is  wet, — the  vegetable  forms,  which  die  or  disap- 
pear at  the  beginning  of  the  dry  season,  reappear 
at  the  beginning  of  the  wet  season.  Areas  of  the 


CONDITIONS  FOR   THE  GROWTH  OF  TREES.     43 

earth  possessing  this  character  of  vegetation  are 
called  steppe  regions. 

"When  the  rainfall  is  not  very  great  in  amount, 
but  is  fairly  well  distributed  throughout  the  year, 
so  that  the  rain  is  never  absent  for  a  very  long 
time,  regions  called  meadows  or  prairies  occur. 

If  there  is  an  abundance  of  moisture  at  nearly  all 
times  throughout  the  year,  so  that  such  moisture 
is  absent  for  no  very  long  time,  then  the  country 
may  be  covered  by  trees.  Such  areas  are  called 
forests. 

Forests  cannot  exist  in  the  temperate  zones  of 
the  earth  in  localities  where,  during  the  time  of 
the  trees'  active  growth,  a  very  long  interval  exists 
during  which  no  rain  falls.  "While  the  active 
growth  of  the  trees  is  temporarily  suspended,  as 
during  the  winter,  this  necessity  for  liquid  nour- 
ishment, of  course,  no  longer  exists. 

The  reason  forests  cannot  grow  except  where 
moisture  is  present  during  nearly  all  the  time  the 
plants  are  growing,  will  be  easily  understood  from 
the  following  considerations : 

Suppose  a  soil  exists  in  any  section  of  country, 
and  such  soil  contains  .germs  of  practically  all 
species  of  plant  life.  "When  such  a  soil  is  sub- 
mitted to  the  action  of  light,  heat,  and  moisture, 


44  OUTLINES  OF  FORESTRY. 

most  of  these  germs  will  be  called  into  active 
growth,  and  various  forms  of  plant  life  will  begin 
their  existence. 

Suppose  this  particular  section  be  a  region 
where,  for  several  months  of  the  year,  no  rain 
falls,  and  whose  soil,  as  is  generally  the  case, 
rapidly  becomes  dry.  During  the  dry  season  all 
forms  of  plant  life  will  die  from  want  of  proper 
nourishment 

On  the  reappearance  of  the  wet  season,  only 
those  forms  of  plant  life  will  appear  that  have 
been  able,  during  the  brief  time  of  the  wet  season, 
to  reach  their  full  maturity  and  produce  their  fruit 
or  seeds,  and  so  supply  the  germs  necessary  for  a 
new  growth.  Such  forms  as  trees,  which,  as  is 
well  known,  require  many  years  to  mature  their 
seed  or  fruit,  will  necessarily  be  unable  to  continue 
to  grow  naturally  in  such  a  region  of  country. 

Of  course,  it  might  easily  happen  that  during 
the  first  wet  season  all  the  germs  might  not  have 
been  called  into  active  life  by  the  combined  influ- 
ence of  the  light  and  heat,  so  that  on  the  next  wet 
season  such  forms  might  again  spring  up  naturally. 

But  their  continued  existence,  under  these  cir- 
cumstances, would  be  impossible  from  the  absence 
of  the  new  germs. 


CONDITIONS  FOR   THE  GROWTH  OF  TREES.     45 

In  any  section  of  country  where  the  rainfall  is 
limited  to  certain  periods  of  the  year,  only  those 
plants  can  continue  to  grow  that,  during  the  time 
the  rain  continues  and  water  is  supplied  to  them, 
or  during  the  time  the  plant  is  actually  growing, 
can  reach  their  maturity  and  develop  their  seeds, 
and  thus  supply  new  germs  that  shall  be  ready 
for  the  appearance  of  the  next  rainy  season. 

For  the  growth  of  forests,  both  a  certain  depth 
of  soil  and,  in  general,  a  certain  character  of  soil 
are  necessary.  This  soil  was  slowly  formed  by  the 
decomposition  of  the  hard,  igneous  rocks  that  origi- 
nally formed  the  entire  crust  of  the  earth,  and 
contains  a  quantity  of  vegetable  mould  or  humua 
derived  from  many  successive  generations  of  plant. 

In  the  beginning,  when  the  rocks'  bare  surfaces 
emerged  from  the  universal  oceans,  forests  could 
not  grow  even  where  the  proper  conditions  of 
light,  heat,  and  moisture  were  present,  until  such 
soil  had  been  prepared  for  them. 

Extensive  forests  can  exist  naturally  only  in 
regions  where  suitable  soil  exists  and  where  the 
rainfall  during  the  time  of  growth  is  maintained 
with  a  certain  approach  towards  regularity,  so 
that  the  trees  are  then  properly  and  continually 
supplied  with  liquid  nourishment. 


46  OUTLINES  OF  FORESTRY. 

It  is  in  the  temperate  regions  of  the  earth  and 
in  some  parts  of  the  tropics  that  the  great  forest 
areas  are  to  be  found,  since  it  is  in  these  regions 
that  the  rain  may  fall  at  almost  any  time  of  day, 
and  on  almost  any  day  of  the  year. 

There  are,  however,  certain  regions  in  the  tropics 
where  forests  exist,  although  there  are  compara- 
tively extended  periods  during  the  growth  of  the 
trees  when  rain  does  not  fall.  Here,  however,  the 
air  is  very  moist,  and  heavy  dews  take  the  place 
of  rain,  or  the  rich  vegetable  humus  absorbs  the 
vapor  directly  from  the  air;  or,  in  some  cases, 
though  growth  is  not  actually  suspended,  it  is  at 
least  so  markedly  retarded  that  the  decreased 
nourishment  of  the  trees  is  less  injurious. 

It  is  especially  on  the  sides  of  mountains,  where 
rain  may  fall  in  no  matter  from  what  direction  the 
wind  comes,  or  on  the  side  of  an  island  or  conti- 
nent that  receives  the  prevalent  wind,  that  forests 
are  to  be  found  in  nearly  all  portions  of  the  earth's 
surface,  provided  the  heat  is  sufficiently  great  and 
a  suitable  soil  is  present.  These  conditions  of  soil 
and  temperature  exist  on  nearly  all  mountain 
slopes  outside  the  polar  regions. 

The  mountains  may,  therefore,  be  regarded  as 
the  natural  home  of  the  forests.  The  mountains 


CONDITIONS  FOR   THE  GROWTH  OF  TREES.     47 

are  also  the  natural  birthplaces  of  the  rivers. 
The  preservation  of  the  forests  on  the  sides  of 
mountains  is  necessary  to  insure  such  a  drainage 
of  the  rainfall  as  will  hest  preserve  the  uniform 
flow  of  the  rivers  and  best  prevent  them  from 
overflowing  their  banks  in  times  of  rain,  or  be- 
coming too  shallow  in  times  of  drought. 

The  preservation  of  the  forests  is  necessary  in 
certain  portions  of  the  lowlands  to  protect  the 
crops  from  the  direct  action  of  winds  that  are 
either  too  hot  or  too  cold. 

When  it  is  necessary  to  cut  down  the  forests  for 
the  sake  of  their  timber,  the  areas  on  which  they 
grew  in  all  cases  should  be  replanted,  so  that 
such  areas  may  be  able  to  yield  continually  suc- 
cessive crops  of  timber  so  necessary  for  man's 
needs. 

As  to  the  necessity  for  an  abundance  of  water 
well  distributed  throughout  the  year  in  order  to 
insure  the  growth  of  trees,  Guyot,  in  his  "  Earth 
and  Man,"  *  says,  on  page  189 : 


*  "  The  Earth  and  Man :  Lectures  on  Comparative  Physical 
Geography  in  its  Relation  to  the  History  of  Mankind,"  by 
Arnold  Guyot.  Boston:  Gould,  Kendall  &  Lincoln,  59 
Washington  Street,  1849. 


48  OUTLINES  OF  FORESTRY. 

"  North.  America,  in  spite  of  its  more  continental  climate, 
shares  no  less  in  this  character  of  the  New  World.  The 
beauty  and  the  extent  of  the  vast  forests  that  cover  its  soil, 
the  variety  of  the  arborescent  species  composing  them,  the 
strong  and  lofty  size  of  the  trees  which  grow  there,  all  these 
are  too  well  known  for  me  to  stop  and  describe  them.  It  is 
because  to  a  more  abundant  irrigation  this  continent  adds  a 
soil  slightly  mountainous,  almost  everywhere  fertile,  securing 
it  always  an  equal  moisture,  a  more  abundant  harvest  of  all 
the  vegetables  useful  to  man." 

Concerning  the  growth  of  trees  on  mountain 
slopes,  iSlisee  Reclus,  in  his  work,  "  The  Ocean,"  * 
says  on  page  383 : 

"  The  stages  of  vegetation  have  been  studied  with  care  on 
the  slopes  of  many  other  mountains  of  temperate  Europe, 
especially  on  the  sides  of  the  Ventoux,  by  M.  Charles  Martins  ; 
but  it  is  in  the  Alps,  above  all,  that  the  most  celebrated  bota- 
nists of  our  country  have  made  their  comparative  researches 
on  the  floras  of  the  various  altitudes.  The  limits  of  these 
floras  vary,  so  far  as  we  can  understand,  according  to  the  form, 
exposure,  and  height  of  the  mountains,  the  nature  of  the 
rocks,  the  moisture  of  the  soil,  and  abundance  of  snow,  and 
the  meteorological  conditions  of  the  surrounding  atmosphere. 
It  is,  therefore,  impossible  to  give  the  precise  figures  on  the 
whole  of  the  Alpine  masses,  and  the  averages  obtained  by 

*  Keprinted,  by  permission,  from  "  The  Ocean,  Atmosphere, 
and  Life,"  by  Elisee  Eeclus.  New  York :  Harper  &  Brothers, 
Publishers,  Franklin  Square,  1874.  Pp.  534. 


CONDITIONS  FOR   THE  GROWTH  OF  TREES.     49 

savants  have  only  a  very  general  value.  Without  taking  ac- 
count of  the  upper  limits  of  cultivation,  which  varies  singu- 
larly in  the  high  valleys  in  proportion  to  the  industry,  intelli- 
gence, and  social  condition  of  the  inhabitants,  we  may  say 
that  the  vegetation  of  the  plain  hardly  exceeds  three  thousand 
feet ;  above  this  height  the  slopes  where  man  has  not  violently 
interfered  to  change  the  productions  of  the  soil  are  naturally 
covered  by  vast  forests.  Still,  the  great  trees  gradually  dimin- 
ish in  height  in  proportion  as  we  rise  into  a  zone  where  the 
air  is  rarer  and  colder ;  their  wood  becomes  harder  and  more 
knotted ;  and  the  hardy  kinds,  which  venture  not  far  from  the 
region  of  the  snows,  end  by  creeping  on  the  ground,  as  if  to 
seek  shelter  between  the  stones.  To  the  north  of  Switzerland, 
the  beech  does  not  exceed  the  height  of  four  thousand  feet, 
and  the  spruce-fir  stops  at  six  thousand  feet.  In  the  group  of 
Monte  Rosa,  the  same  forest  growth,  which  approaches  most 
nearly  to  the  zone  of  perpetual  snow,  ascends  as  far  as  six 
thousand  two  hundred  feet  on  the  northern  slope ;  while  on 
the  opposite  side  the  larch,  still  hardier,  attains  its  upper 
limit  at  seven  thousand  two  hundred  feet.  Higher  still  we 
only  find  the  fantastically  twisted  trunks  of  a  few  mugho  pines, 
rhododendrons,  willow-herbs,  and  juniper-trees ;  then  all  vege- 
tation becomes  more  stunted,  and  is  attached  to  the  ground  in 
order  to  escape  the  icy  winds,  and  to  allow  of  its  being  covered 
in  winter  with  a  protecting  layer  of  snow  up  to  the  very  edges 
of  the  glacier  and  the  white  surface  of  the  snows." 


50  OUTLINES  OF  FORESTRY. 


V.    THE   FORMATION   OF   SOIL. 

THE  soil,  in  which  the  plant  grows  and  which 
forms  its  cradle,  is  composed  chiefly  of  mineral 
matters  derived  from  the  originally  crystalline 
rocks  which  were  formed  by  the  gradual  cooling 
of  the  earth's  crust.  The  soil,  however,  also  con- 
tains a  small  quantity  of  vegetable  mould  or 
humus,  obtained  by  the  growth  and  subsequent 
decay  of  successive  generations  of  plants. 

Before  soil  can  be  formed,  the  hard  crystalline 
rocks  must  be  broken  up,  or,  as  it  is  technically 
called,  disintegrated. 

This  disintegration  is  effected  to  some  slight 
degree  by  the  roots  of  plants,  but  it  is  mainly 
brought  about  by  the  action,  in  one  way  or  an- 
other, of  water. 

Soils  are  divided  by  Gray  into  gravelly,  sandy, 
clayey,  calcareous,  loamy,  and  peaty. 

Gravelly  soils  are  such  as  have  coarse  pebbles 
or  fragments  of  quartz,  lime,  or  feldspar  spread 
through  more  finely  divided  mineral  matter. 

Sandy  soils  are  usually  formed  of  fine  particles 


THE  FORMATION  OF  SOIL.  51 

of  quartz,  associated  with,  feldspar.  Such  soils 
generally  contain  some  compound  of  iron. 

Clayey  soils  are  formed  from  the  decomposition 
of  feldspathic  rocks.  They  are  impervious  to 
water  and  harden  on  drying. 

Calcareous  soils  contain  carbonate  of  lime  in 
large  amounts. 

Peaty  soils  are  such  as  contain  a  large  proportion 
of  partially  decayed  vegetable  matter. 

The  soil  is  sometimes  found  resting  in  place, 
directly  on  top  of  the  rocks  from  which  it  was 
derived.  In  such  cases  its  various  mineral  ingre- 
dients can  be  traced  directly  to  the  decomposition 
of  the  underlying  rocks. 

A  section  of  such  rock  and  soil  will  show  the 
rock  gradually  passing  from  the  loose  soil  into  the 
hard  and  unchanged  rock. 

In  other  cases  the  soil  is  found  at  a  considerable 
distance  from  the  locality  in  which  it  was  originally 
formed,  or  in  which  the  plants  grew  that  produced 
its  vegetable  mould. 

The  soil  is  carried  from  the  rocks  from  which 
its  mineral  ingredients  were  derived  either  by  the 
action  of  the  winds  or  by  the  waters,  though 
mainly  by  the  latter,  to  distances  which  often  reach 
thousands  of  miles. 


52  OUTLINES  OF  FORESTRY. 

"Where  the  soil  remains  directly  on  the  surface  of 
the  rocks  from  which  it  was  derived,  it  is  interest- 
ing to  trace  the  gradual  changes  that  occur  in 
passing  downward  from  the  loose  soil  to  the  hard, 
unchanged  rock  below.  On  top  is  the  loose  soil, 
with  the  admixture  of  vegetable  humus  so  neces- 
sary to  the  growth  of  the  higher  forms  of  vege- 
table life.  Under  this  is  thoroughly  broken-up 
rock,  which  contains  less  vegetable  matter.  Under 
this  is  coarser  and  less  broken-up  rock.  Under 
this  the  rock  is  intact  and  merely  softened  by 
the  agencies  effecting  the  disintegration.  Finally, 
lying  under  all,  is  the  still  untouched  virgin  rock. 

The  principal  agencies  causing  the  disintegration 
of  rocks  are : 

1.  The  expansive  force  which  sprouting  or  grow- 
ing vegetation  exerts  on  the  rock. 

2.  The   alternate    expansions    and    contractions 
that  attend  the  freezing  and  thawing  of  the  water 
which  flows  into  the  crevices  between  the  rocks, 
or  sinks  into  their  porous  structure. 

3.  The  erosion  or  cutting  power  of  water  charged 
with  suspended  matter  or  sediment. 

4.  The  erosion  or  cutting  of  glaciers  or  masses 
of  moving  ice. 

5.  The  solvent  power  of  water,  especially  when 


THE  FORMATION  OF  SOIL.  53 

aided  by  the  chemical  action  of  such  gases  as 
oxygen  and  carbonic  acid  gas  dissolved  in  the 
water. 

During  the  vigorous  growth  of  any  form  of 
plant  life  the  increase  in  the  length  and  diameter 
of  the  roots  will  break  up  or  disintegrate  even  the 
hardest  of  rocks.  This  action  is  especially  effec- 
tive from  the  fact  that  in  many  cases  the  roots  ex- 
tend for  the  greater  part  through  crevices  or  cracks 
where  the  quantity  of  moisture  is  greater  than 
elsewhere. 

The  effects  of  alternate  expansion  and  contrac- 
tion are  limited  to  climates  where  the  temperature 
occasionally  falls  below  the  freezing-point  of  water. 
The  water  sinking  into  the  porous  rocks,  and  fill- 
ing the  crevices  and  cracks  between  them,  expands 
on  freezing  and  breaks  the  rock  into  fragments. 
These  fragments  are  afterwards  broken  into  smaller 
fragments,  until  the  pieces  are  sufficiently  small  to 
be  carried  by  the  winds  and  waters  to  distant 
localities. 

The  ability  of  running  water  charged  with  sus- 
pended mineral  matter  to  cut  or  wear  away  hard 
rocks  is  very  great.  The  moving  water  carries 
mechanically  suspended  in  it  minute  fragments  of 
such  hard  minerals  as  angular  fragments  of  quartz 

6* 


54  OUTLINES  OF  FORESTRY. 

or  pebbles.  These  act  as  planes,  cutters,  or  chisels 
that  gnaw,  cut,  or  wear  away  even  the  hardest 
rock.  This  process  is  technically  called  erosion, 
and  is  of  great  aid  in  the  formation  of  soil. 

There  collects  on  the  sides  of  mountains  above 
the  limit  of  perpetual  snow  an  immense  accumula- 
tion of  snow,  which,  through  gradual  pressure,  is 
converted  into  hard  ice,  and  forms  masses  called 
glaciers.  The  glaciers  slowly  move  or  slip  down 
the  sides  of  the  mountain.  They  receive  the 
drainage  of  snow  from  the  slopes  of  the  valleys 
through  which  they  move,  just  as  rivers  receive  the 
drainage  of  liquid  water.  The  glaciers  carry  with 
them  considerable  mineral  matter,  both  in  the 
shape  of  small  rocks  and  large  boulders.  As  the 
mass  moves  down  the  mountains,  this  mineral 
matter  is  pressed  against  the  sides  of  the  val- 
leys, or  along  the  bottom  of  the  bed  through 
which  it  is  moving,  and  cuts,  grooves,  or  grinds 
the  hard  rocks,  and  thus  aids  in  the  production 
of  soil. 

From  its  great  solvent  power,  water  is  able  to 
finally  sink  into  what  were  originally  impervious 
rocks,  by  gradually  dissolving  out  the  soluble 
portions  of  the  rocks.  In  this  way  the  rock  is  ren- 
dered rotten  by  the  removal  of  the  materials  which 


THE  FORMATION  OF  SOIL.  55 

formerly  acted  as  a  cement  to  bind  its  different 
ingredients  together.  "When  charged  with  either 
oxygen  or  cabonic  acid  gas,  derived  generally 
directly  from  the  air,  the  chemical  action  of  these 
dissolved  gases  greatly  aids  the  water  in  break- 
ing up,  and  thus  rendering  partly  porous,  even  the 
hardest  of  the  igneous  rocks. 

Let  us  take,  for  example,  some  of  the  com- 
monest minerals  of  the  igneous  rocks,  such  as 
quartz,  feldspar,  and  mica. 

None  of  these  ingredients  are  very  soluble  in 
pure  water ;  but  if  the  water  contains  oxygen  and 
carbonic  acid  gas  in  solution,  the  feldspar  will  be 
gradually  broken  up,  and  the  hard  granites  or 
gneisses,  which  form  so  large  a  portion  of  the 
igneous  rocks,  will  be  gradually  disintegrated. 
From  the  feldspar  will  be  derived  the  kaolins  or 
clays,  and  the  water  percolating  through  them 
will  be  charged  with  a  small  quantity  of  potash, 
so  necessary  for  the  growth  of  plants. 

Limestones  are  readily  disintegrated  by  water 
which  contains  carbonic  acid  in  solution,  and  from 
such  rocks  are  derived  the  calcareous  matter  so 
necessary  to  plant-growths. 

The  carbonic  acid  dissolved  in  water  sometimes 
acts  to  considerably  change  the  character  of  the 


56  OUTLINES  OF  FORESTRY. 

soil,  by  effecting  new  combinations  of  its  mineral 
constituents. 

Some  soils  possess  the  very  valuable  property  of 
absorbing  water  vapor  directly  from  the  atmos- 
phere and  condensing  it  in  their  pores.  This 
property  is  exceedingly  valuable  during  times  of 
extended  droughts,  when  a  considerable  quantity 
of  vapor  may  be  present  in  the  air.  Of  all  soils, 
those  containing  the  greatest  quantity  of  vegetable 
mould  or  humus  possess  this  valuable  property  in 
the  greatest  degree.  Clayey  soils  also  possess  it 
to  a  marked  degree. 

Soils  also  possess  the  power  of  absorbing  gases,. 
Ordinarily,  most  soils  contain  of  absorbed  gases 
a  smaller  proportion  of  oxygen  and  more  carbonic 
acid  gas  than  the  atmosphere. 

The  ability  of  soils  to  absorb  the  sun's  heat 
varies  with  their  color;  as  a  rule,  dark-colored 
soils  absorb  the  heat  more  rapidly  than  light- 
colored  soils. 

Darwin  has  shown  that  in  certain  localities  the 
common  earthworm  greatly  aids  in  the  formation 
and  physical  character  of  the  soil  by  extensive  bur- 
rowing and  tunnelling. 

In  all  cases,  however,  the  process  by  which  the 
soil  is  formed  is  a  gradual  one ;  and  since  there  is 


THE  FORMATION  OF  SOIL.  57 

necessarily  mingled  with  such  finely  broken-up 
mineral  matters  a  quantity  of  vegetable  humus 
derived  from  the  decay  of  successive  generations 
of  plants,  its  formation  is  rendered  still  more 
gradual. 

In  wooded  districts,  where  a  carpet  of  decaying 
leaves  covers  a  large  part  of  the  ground  during 
most  of  the  year,  the  water  that  soaks  into  such 
porous  soil  naturally  contains  a  larger  quantity 
of  carbonic  acid  than  would  water  that  had  not 
previously  been  passed  through  such  matter.  This 
dissolved  carbonic  acid,  from  its  chemical  action 
on  the  ingredients  of  the  rock,  greatly  aids  the 
water  in  forming  new  soil. 

Speaking  of  the  loss  of  the  vegetable  mould, 
gained  by  the  patient  accumulation  of  different 
generations  of  plants  through  passing  centuries, 
M.  de  Bouville,  a  Prefect  of  the  lower  Alps,  in  a 
report  to  the  Government,  quoted  by  Marsh  on 
page  540  of  "  The  Earth  as  Modified  by  Human 
Action,"  *  writes  as  follows  : 


*  Eeprinted,  by  permission,  from  "  The  Earth  as  Modified 
by  Human  Action,"  by  George  P.  Marsh.  New  York :  Scrib- 
ner,  Armstrong  &  Co.,  654  Broadway,  New  York,  1874.  Pp. 
656. 


58  OUTLINES  OF  FORESTRY. 

"  It  is  certain  that  the  productive  mould  of  the  Alps,  swept 
off  by  the  increasing  violence  of  that  curse  of  the  mountains, 
the  torrents,  is  daily  diminishing  with  fearful  rapidity.  All 
our  Alps  are  wholly,  or  in  large  proportion,  bared  of  wood. 
Their  soil,  scorched  by  the  sun  of  Provence,  cut  up  by  the 
hoofs  of  the  sheep,  which,  not  finding  on  the  surface  the  grass 
they  require  for  their  sustenance,  gnaw  and  scratch  the  ground 
in  search  of  roots  to  satisfy  their  hunger,  is  periodically  washed 
and  carried  off  by  melting  snows  and  summer  storms. 

"  I  will  not  dwell  on  the  effects  of  the  torrents.  For  sixty 
years  they  have  been  too  often  depicted  to  require  to  be  further 
discussed,  but  it  is  important  to  show  that  their  ravages  are 
daily  extending  the  range  of  devastation.  The  bed  of  the 
Durance,  which  now  in  some  places  exceeds  a  mile  and  a 
quarter  in  width,  and,  at  ordinary  times,  has  a  current  of 
water  less  than  eleven  yards  wide,  shows  something  of  the 
extent  of  the  damage.  Where,  ten  years  ago,  there  were 
still  woods  and  cultivated  grounds  to  be  seen,  there  is  now 
but  a  vast  torrent ;  there  is  not  one  of  our  mountains  which 
has  not  at  least  one  torrent,  and  new  ones  are  daily  forming." 

The  power  of  a  glacier  with,  its  fragments  of 
rocks  to  erode  the  valleys  through  which  it  passes 
is  thus  referred  to  by  Le  Conte,  in  his  "  Elements 
of  Geology,"  *  on  page  51. 

*  Eeprinted,  by  permission,  from  the  "  Elements  of  Ge- 
ology," by  Joseph  Le  Conte,  Professor  of  Geology  and  Natural 
History  in  the  University  of  California.  New  York :  D. 
Appleton  &  Co.,  551  Broadway,  1878.  Pp.  588. 


THE  FORMATION  OF  SOIL.  59 

"  When  we  consider  the  weight  of  glaciers  and  their  un- 
yielding nature  as  compared  with  water,  it  is  easy  to  see  that 
their  erosive  power  must  be  very  great.  This  is  increased 
immensely  by  fragments  of  stone  of  every  conceivable  size 
carried  along  between  the  glacier  and  its  bed.  These  partly 
fall  in  at  the  sides  and  become  jammed  between  the  glacier 
and  the  confining  rocks,  partly  fall  into  the  crevasses  and  work 
their  way  to  the  bed,  and  partly  are  torn  from  the  rocky  bed 
itself.  The  effects  of  glacier  erosion  differ  entirely  from  those 
of  water  :  1.  Water,  by  virtue  of  its  perfect  fluidity,  wears  away 
the  softer  spots  of  the  rock  and  leaves  the  harder  standing  in 
relief;  while  a  glacier,  like  an  unyielding  rubber,  grinds  both 
hard  and  soft  to  one  level.  This,  however,  is  not  so  absolutely 
true  of  glaciers  as  might  be  supposed.  Glaciers,  for  reasons  to 
be  discussed  hereafter,  conform  to  large  and  gentle  inequalities 
of  their  beds,  though  not  to  small  ones,  acting  thus  like  a  very 
stiffly  viscous  body.  Thus,  their  beds  are  worn  into  very  re- 
markable and  characteristic  smooth  and  rounded  depressions 
and  elevations  called  roches  mouton'ees.  Sometimes  large  and 
deep  hollows  are  swept  out  by  a  glacier  at  some  point  where 
the  rock  is  softer,  or  where  the  slope  of  the  bed  changes  sud- 
denly from  a  greater  to  a  less  angle.  If  the  glacier  should 
subsequently  retire,  water  accumulates  in  these  excavations 
and  forms  lakelets.  Such  lakelets  are  common  in  old  glacier 
beds." 

Geikie  thus  describes  the  formation  of  soil  in 
his  "  Text-Book  of  Geology,"  *  on  page  339  : 

*  Eeprinted,  by  permission,  from  "  Text-Book  of  Geology," 
by  Archibald  Geikie,  LL.D.,  F.B.S,  Director  of  the  Geo- 


60  OUTLINES  OF  FORESTRY. 

"  On  level  surfaces  of  rock  the  weathered  crust  may  remain 
with  comparatively  little  rearrangement  until  plants  take  root 
on  it,  and  by  their  decay  supply  organic  matter  to  the  de- 
composed layer,  which  eventually  becomes  what  we  term 
'vegetable  soil.'  Animals  also  furnish  a  smaller  proportion 
of  organic  ingredients.  Though  the  character  of  the  soil  de- 
pends primarily  upon  the  nature  of  the  rock  out  of  which  it 
has  been  formed,  its  fertility  arises  in  no  small  measure  from 
the  commingling  of  decayed  animal  and  vegetable  matter  with 
decomposed  rock. 

"  A  gradation  may  be  traced  from  the  soil  downwards  into 
what  is  termed  the  '  subsoil,'  and  thence  into  the  rock  under- 
neath. Between  the  soil  and  the  subsoil  a  marked  difference 
in  colour  is  often  observable,  the  former  being  yellow  or  brown, 
when  the  latter  is  blue,  gray,  red,  or  other  colour  of  the  rock 
beneath.  This  contrast,  evidently  due  to  the  oxidation  and 
hydration  especially  of  the  iron,  extends  downwards  as  far  as 
the  subsoil  is  opened  up  by  the  rootlets  and  fibres  to  the 
ready  descent  of  rain-water.  The  yellowing  of  the  soil  may 
even  be  occasionally  noticed  around  some  stray  rootlet  which 
has  struck  down  farther  than  the  rest,  below  the  general  limit 
of  the  soil." 

logical  Survey  of  Great  Britain  and  Ireland,  etc.,  etc.    London : 
Macmillan  &  Co.,  1882.    Pp.  971. 


THE  INANIMATE  ENEMIES  OF  THE  FOREST.      61 


VI.     THE    INANIMATE   ENEMIES   OF 
THE   FOREST. 

LIKE  other  forms  of  animate  nature,  the  forest 
is  compelled  to  make  a  continual  struggle  for  ex- 
istence. In  order  that  it  may  continue  to  exist, 
the  conditions  requisite  for  its  growth  must  be 
maintained,  and  the  influences  that  oppose  such 
growth  must  be  held  in  check. 

The  character  of  the  vegetation  that  covers  any 
region  of  the  earth  is  dependent  not  only  on  the 
character  of  its  soil,  but  also  on  the  peculiarities 
of  its  climate ;  such,  for  example,  as  the  distribu- 
tion of  the  temperature  throughout  the  year,  the 
distribution  of  the  moisture,  etc. 

There  is  in  the  vegetable  as  in  the  animal  world 
a  veritable  struggle  for  existence.  Given  a  partic- 
ular character  of  soil  and  climate  in  any  locality, 
the  plants  that  will  continue  to  grow  in  such 
locality  will  be  those  that  are  best  fitted  to  exist 
there  naturally. 

At  first  all  forms  may  appear ;  but  some  partic- 
ular form  may  be  so  much  better  suited  to  the 

6 


62  OUTLINES  OF  FORESTRY. 

natural  conditions  of  the  locality,  that  it  will  grow 
and  multiply  so  rapidly  as  to  choke  out  of  exist- 
ence all  other  forms.  Even  such  forms,  however, 
will  continue  to  exist  only  as  long  as  the  condi- 
tions continue  favorahle  for  their  existence. 

The  dependence  of  plant  life  on  climatic  condi- 
tions is,  perhaps,  more  marked  in  the  higher 
forms  of  the  vegetable  world.  Trees  may,  in  a 
certain  sense,  be  regarded  as  of  the  highest  type  of 
plant  life.  They  rigorously  depend  on  conditions 
of  soil  and  climate  for  their  continued  existence. 
It  is  true  that  when  a  forest  is  once  formed,  and  its 
vigorous  growth  has  almost  completely  shut  out 
the  light  from  the  soil  in  which  it  is  growing,  that 
the  numerous  forms  of  vegetable  life  which  lie 
ready  to  spring  up,  should  the  sun's  rays  find  free 
access  to  them,  are  prevented  from  growing.  Even 
if  they  did  appear,  and  the  climatic  conditions 
remained  as  before,  the  same  struggle  for  existence 
would  again  occur,  and  the  same  forest  would  in 
all  probability  finally  be  reproduced.  If,  however, 
the  character  of  the  soil  be  altered,  or  the  climatic 
or  other  conditions  be  changed,  the  forests  would 
either  disappear  or  be  replaced  by  trees  of  another 
character. 

The  forest  has  many  enemies  that  are  ready  at 


TEE  INANIMATE  ENEMIES  OF  THE  FOREST.      63 

all  times  to  resist  its  growth,  and  even  to  sweep  it 
out  of  existence. 

The  soil  is  continually  undergoing  a  small 
change  in  composition  as  the  different  growths  of 
plants  appear  and  disappear. 

The  earth's  climate  is  at  present  undergoing  but 
very  little  change.  In  the  geological  past  such 
changes  were  so  far-reaching  and  severe  that  they 
were  followed  by  pronounced  changes  in  both  the 
animal  and  plant  life.  The  comparatively  small 
changes  that  have  occurred  within  historical  time 
are,  perhaps,  rather  to  be  regarded  as  some  of  the 
effects  produced  by  the  disappearance  of  certain 
forms  of  plant  life,  than  as  the  causes  of  such 
disappearance. 

The  exact  balance  of  conditions  that  permit  the 
continued  existence  of  forests  is  so  delicate,  that 
causes,  comparatively  insignificant  in  themselves, 
may  finally  produce  marked  effects. 

The  enemies  of  the  forest  may  be  divided  into 
two  classes : 

1.  Inanimate. 

2.  Animate. 

The  principal  inanimate  enemies  of  the  forest 
are: 
a.  Fire. 


64  OUTLINES  OF  FORESTRY. 

b.  "Winds. 

c.  Floods. 

d.  Avalanches. 

The  principal  animate  enemies  of  the  forest  are : 

a.  Plants. 

b.  Animals. 

c.  Man. 

Limiting  our  consideration,  for  the  present,  to 
the  inanimate  enemies  of  the  forest,  we  will  dis- 
cuse  the  manner  in  which  each  of  these  enemies 
tends  to  destroy  the  forest. 

Fire. — The  destruction  of  the  forest  by  fire 
sometimes  results  finally  in  a  more  complete  loss 
than  by  any  other  cause.  In  case  of  the  intelligent 
removal  of  the  forest  by  the  axe  of  the  lumber- 
man, only  the  larger  trees  are  cut  down,  and  the 
smaller  ones  that  are  left,  getting  more  heat,  light, 
and  nourishment,  grow  rapidly,  and  are,  in  turn, 
soon  ready  for  removal  by  the  axe,  thus  to  give 
place  to  others. 

Fire,  however,  generally  removes  both  great  and 
small. 

While  a  fire  may  sometimes  increase  the  growth 
of  forests,  as  in  the  case  of  the  pitch  pine  by  the 
destruction  of  the  less  hardy  forms  of  plant  life, 
the  destruction  of  the  forest  by  fire,  especially  on 


THE  INANIMATE  ENEMIES  OF  THE  FOREST.      65 

the  slopes  of  mountains,  is  often  so  complete  that 
before  a  new  vegetation  can  appear,  the  rapid 
drainage  of  the  slopes  is  attended  by  such  a  loss 
of  the  soil  as  to  render  such  slopes  unfit  to  repro- 
duce the  forest  trees  for  a  period  of  time  much 
longer  than  the  life  of  the  average  man. 

Forest  fires  are  generally  kindled  during  the 
drier  seasons  of  the  year.  Under  these  conditions 
the  rain  which  subsequently  falls  is  apt  to  carry 
off  so  much  of  the  soil  that,  even  should  the  trees 
again  appear,  the  remaining  soil  would  probably  be 
insufficient  in  quantity  to  bring  them  to  maturity. 

The  causes  of  forest  fires  are  to  be  found  in 
camp-fires  of  the  lumberman,  the  burning  of 
brush,  the  locomotive  spark,  the  lightning  bolt, 
and,  perhaps,  at  times,  to  the  heating  power  of 
the  sun's  rays,  concentrated  by  nodules  of  gum  or 
resin,  acting  as  burning-glasses. 

In  the  case  of  newly-settled  countries,  fires  have 
been  sometimes  purposely  started,  for  the  purpose 
of  readily  obtaining  an  extended  pasturage. 

The  rapidity  with  which  a  forest  fire  spreads 
depends,  of  course,  on  the  character  of  the  trees 
and  the  force  of  the  wind.  It  is  also,  however, 
dependent  largely  on  the  character  of  the  soil.  A 
rocky  or  sandy  soil  permits  a  fire  to  spread  much 

e  6* 


66  OUTLINES  OF  FORESTRY. 

more  rapidly  than  a  damp  soil.  Some  forests  of 
soft  and  readily  ignitible  wood  have  a  covering  of 
moss  on  the  soil,  which  permits  the  fire,  when  once 
started,  to  spread  with  awful  rapidity. 

Extensive  tracts  in  South  America,  capable  of 
sustaining  dense  forests,  and  originally  covered  by 
such,  are  now  prevented  from  so  doing  by  fires 
that  are  systematically  started  every  year,  for  the 
purpose  of  obtaining  a  new  growth  of  grass  for 
pasturage. 

The  power  of  the  wind  in  causing  the  destruc- 
tion of  the  forest  is,  to  a  great  extent,  limited  to 
the  edges  of  the  forest.  In  the  midst  of  the  forest, 
the  trees  stand  so  close  together  that  they  shield 
one  another  from  the  force  of  the  wind.  If,  how- 
ever, an  opening  is  made  by  the  axe  of  the  lumber- 
man, by  fire,  or  by  any  other  cause,  the  wind  may 
cut  a  wide  swath  through  the  forest,  and  thus 
destroy  many  noble  trees. 

"When  rivers  overflow  their  banks,  thousands  of 
acres  of  forest  trees  are  often  swept  away,  and  in 
this  manner  considerable  changes  may  occur  in 
the  general  character  of  such  districts. 

The  timber  thus  thrown  into  the  river  channel 
often  forms  accumulations  called  rafts,  which,  be- 
coming fixed  in  certain  parts  of  the  stream,  tend 


THE  INANIMATE  ENEMIES  OF  THE  FOREST.      67 

to  retard  the  free  drainage  of  the  country,  and 
often  result  in  marked  changes  in  the  river  chan- 
nel. Such  rafts  are  still  found  in  the  Mackenzie 
Biver,  and  formerly  existed  in  parts  of  the  Missis- 
sippi and  the  Red  Rivers. 

The  effects  of  the  avalanche  in  sweeping  away 
entire  forests  from  the  mountain  slopes  are  well 
known.  Like  the  influence  of  the  wind,  this  effect 
is  at  first  limited  to  the  edges  of  the  forest.  If 
the  forests  are  preserved,  the  further  movement  of 
the  avalanche  may  be  checked.  In  most  moun- 
tainous countries,  forests  skirting  villages  are  pre- 
served by  rigorous  penal  laws. 

The  protection  from  the  destructive  effects  of 
avalanches  afforded  by  forests  on  mountain  slopes 
is  shown  in  the  following  statement  by  ^lisee 
Reclus  in  a  work  entitled,  "  The  Earth,"  *  on  page 
171: 

"  The  protecting  woods  of  Switzerland  and  the  Tyrol  used  to 
be  defended  by  the  national  bann,  and,  as  it  were,  '  tabooed/ 
They  were,  and  still  are,  called  the  Bannwoelder.  In  the 
valley  of  the  Andermatt,  at  the  northern  foot  of  the  St.  Goth- 

*  Reprinted,  by  permission,  from  "  The  Earth,"  by  Elisee 
Eeclus.  New  York :  Harper  &  Brothers,  Publishers,  Franklin 
Square.  Pp.  573. 


68  OUTLINES  OF  FORESTRY. 

ard,  the  penalty  of  death  was  once  adjudged  on  any  man 
found  guilty  of  having  made  an  attempt  on  the  life  of  one  of 
the  trees  which  shielded  the  habitations.  Added  to  this,  a 
sort  of  mystic  curse  was  thought  to  hang  over  this  impious 
action,  and  it  was  told  with  horror  how  drops  of  blood  flowed 
when  the  smallest  branch  was  broken  off.  It  was  true  enough 
that  the  destruction  of  each  tree  might  perhaps  be  expatiated 
by  the  death  of  a  man." 

"  The  village  and  the  great  establishment  of  the  baths  at 
Bareges,  in  the  Pyrenees,  used  to  be  menaced  every  year  by 
avalanches  rushing  down  from  an  elevation  of  four  thousand 
feet,  at  an  angle  of  thirty-five  degrees.  The  inhabitants, 
therefore,  were  in  the  habit  of  leaving  vacant  spaces  between 
the  two  quarters  of  the  Bareges,  so  as  to  allow  a  free  passage 
to  the  descending  masses.  Lately,  however,  they  have  en- 
deavored to  do  away  with  the  avalanches  by  means  somewhat 
similar  to  those  employed  by  the  Swiss  mountaineers.  They 
have  thrown  up  banks  from  ten  to  twelve  feet  broad  on  the 
sides  of  the  ravines,  and  have  furnished  these  banks  with  an 
edging  of  cast-iron  piles.  Basket-work,  and,  here  and  there, 
walls  of  masonry,  protect  the  young  growing  trees,  which  are 
gradually  improving  under  the  protection  of  these  defensive 
works.  In  the  mean  time,  until  the  real  trees  are  strong 
enough  to  arrest  the  course  of  the  snow,  the  artificial  trees 
have  well  fulfilled  the  end  they  were  destined  for.  In  1860, 
the  year  the  defensive  works  were  finished,  the  only  avalanche 
which  slid  into  the  ravine  did  not  exceed  four  hundred  cubic 
yards  in  bulk ;  while  the  masses  which  used  to  fall  down  upon 
the  Bardges  sometimes  attained  to  more  than  ninety  thousand 
yards  in  volume." 


THE  INANIMATE  ENEMIES  OF  THE  FOREST.      69 

Lyell,  in  his  "  Principles  of  Geology,"  *  on  page 
440,  speaks  thus  of  the  rafts  in  the  Mississippi : 

"  One  of  the  most  interesting  features  in  the  great  rivers  of 
this  part  of  America  is  the  frequent  accumulation  of  what 
are  termed  '  rafts/  or  masses  of  floating  trees,  which  have 
been  arrested  in  their  progress  by  snags,  islands,  shoals,  or 
other  obstructions,  and  made  to  accumulate,  so  as  to  form 
natural  bridges  across  the  stream.  One  of  the  largest  of  these 
was  called  the  raft  of  the  Atchafalaya,  an  arm  of  the  Missis- 
sippi, which  branches  off  a  short  distance  below  its  junction 
with  the  Red  Eiver.  The  Atchafalaya,  being  in  a  direct  line 
with  the  general  direction  of  the  Mississippi,  catches  a  large 
portion  of  the  timber  annually  brought  down  from  the  north ; 
and  the  drift  trees  collected  in  about  thirty-eight  years  previ- 
ous to  1816  formed  a  continuous  raft,  no  less  than  ten  miles  in 
length,  two  hundred  and  twenty  yards  wide,  and  eight  feet 
deep.  The  whole  rose  and  fell  with  the  water,  yet  was  covered 
with  green  bushes  and  trees,  and  its  surface  enlivened  in  the 
autumn  by  a  variety  of  beautiful  flowers.  It  went  on  in- 
creasing till  about  1835,  when  some  of  the  trees  upon  it  had 
grown  to  the  height  of  about  sixty  feet.  Steps  were  then  taken 
by  the  State  of  Louisiana  to  clear  away  the  whole  raft  and 
open  the  navigation,  which  was  effected,  not  without  great 
labor,  in  the  space  of  four  years." 

Dana,  in  his  "  Manual  of  Geology,"  f  on  page 

*  "  Principles  of  Geology,"  by  Charles  Lyell.     London : 
Murray,  1872.    Pp.  671. 
f  Reprinted,  by  permission,  from  a  "Manual  of  Geology," 


70  OUTLINES  OF  FORESTRY. 

657,  gives  the  following  description  of  the  raft  of 
the  Red  River : 

"  The  quantity  of  wood  brought  down  by  some  American 
rivers  is  very  great.  The  well-known  natural '  raft'  obstruct- 
ing the  Bed  Kiver  had  a  length,  in  1854,  of  thirteen  miles,  and 
was  increasing  at  the  rate  of  one  and  a  half  to  two  miles  a 
year,  from  the  annual  accessions.  The  lower  end,  which  was 
then  fifty-three  miles  above  Shreveport,  had  been  gradually 
moving  up  stream,  from  the  decay  of  the  logs,  and  formerly 
was  at  Natchitoches,  if  not  still  farther  down  the  stream. 
Both  this  stream  and  the  other  carry  great  numbers  of  the 
logs  to  the  delta." 

by  James  D.  Dana.    New  York :  Ivison,  Blakeman,  Taylor 
and  Co.,  Publishers.    Triibner  &  Co.,  London.    Pp.  911. 


THE  ANIMATE  ENEMIES  OF  THE  FOREST.      71 


VII.   THE   ANIMATE   ENEMIES  OF  THE 
FOREST. 

THE  animate  or  living  enemies  of  the  forest 
are : 

1.  Plants. 

2.  Animals. 

3.  Man. 

In  classifying  the  enemies  of  the  forest  as  ani- 
mate and  inanimate,  it  should  he  borne  in  mind 
that  the  animate  enemies  of  the  forest  often  call 
to  their  aid  the  powers  of  inanimate  nature.  An 
example  of  this  is  seen  in  the  case  of  the  destruc- 
tion of  forests  hy  fire,  which  are  more  frequently 
started  by  man  than  in  any  other  way. 

The  influence  of  plants  on  the  destruction  of 
forests  is  limited  mainly  to  the  natural  struggle 
which  exists  between  the  different  forms  of  plant 
life  for  the  possession  of  the  soil.  There  are, 
however,  many  forms  of  parasitic  plants,  which, 
growing  on  the  tallest  and  most  vigorous  trees, 
often  in  the  end  cause  their  destruction. 

A  disease  common  in  parts  of  Germany,  called 


72  OUTLINES  OF  FORESTRY. 

the  "  schullkrankheit,"  often  affects  the  pine  for- 
ests. Trees  attacked  by  this  disease  soon  present 
the  appearance  of  having  been  burnt  over,  their 
boughs  and  branches  rapidly  dying  or  drying  up. 
The  cause  of  the  disease  is  not  exactly  known.  It 
has,  however,  been  ascribed  to  the  presence  of  a 
fungous  growth. 

In  some  parts  of  Iowa  a  fungous  growth  on  the 
cottonwood  trees  has  resulted  in  considerable  dam- 
age to  them.  The  fungus  appears  as  an  orange- 
yellow  dust  on  the  lower  surfaces  of  the  leaves. 

The  animal  enemies  of  the  forest,  like  the  winds, 
running  water,  or  the  avalanche,  produce  their 
most  marked  action  on  the  borders  or  edges  of  the 
forest. 

In  the  deep  recesses  of  the  forest  the  vegetable 
kingdom  holds  almost  undisputed  sway.  The  life- 
giving  power  of  the  sun's  light,  and,  to  a  great 
extent,  that  of  its  heat,  are  dissipated  by  the  dense 
foliage  that  almost  completely  shuts  out  the  light 
from  the  dank,  gloomy  ground.  Animal  life,  to 
a  great  extent,  is  crowded  out.  "Wherever  the 
sunlight  freely  enters,  animal  life  appears  in 
myriad  forms,  until  at  length  the  forest  again 
chokes  it  out  of  existence. 

The  animal  enemies  of  the  forest  are  too  numer- 


THE  ANIMATE  ENEMIES  OF  THE  FOREST.      73 

ous  to  be  more  than  merely  mentioned.  The 
following  are  among  some  of  the  more  important : 

Domestic  animals,  which,  when  allowed  to  range 
freely  through  the  woods,  often  cause  much 
damage  by  gnawing  at  the  bark  of  trees,  or,  in 
some  cases,  by  the  destruction  of  the  foliage. 

Among  wild  animals,  the  rodents  effect  the 
greatest  destruction  by  devouring  the  bark,  and 
often  completely  girdling  the  trees.  Among  the 
worst  of  the  rodents  may  be  mentioned  rabbits 
and  mice,  which  gnaw  the  bark,  or  gophers,  which 
eat  the  roots.  Beavers,  too,  destroy  forests,  not 
only  by  the  actual  cutting  down  of  the  trees,  but 
especially  by  building  dams,  and  thus,  by  causing 
the  overflow  of  the  intervale,  destroying  all  its 
growing  timber. 

Goats  and  other  animals  live  largely  on  the 
bark  of  trees.  In  certain  parts  of  the  earth,  such, 
for  example,  as  Assyria,  Greece,  Italy,  Spain,  and 
Morocco,  the  extensive  forests  which  once  covered 
them  have  been  completely  destroyed  by  the 
ravages  of  goats. 

In  general,  insects  damage  trees  by  feeding  on 
the  parts  necessary  for  growth  and  reproduc- 
tion. Some  insects  damage  trees  by  boring  the 
trunks  and  branches  in  order  to  deposit  their 

D  7 


74  OUTLINES  OF  FORESTRY. 

eggs.  In  all  cases  the  increase  in  the  destruction 
produced  by  insect  life  can  be  traced  to  the  indis- 
criminate and  foolish  slaughter  of  the  insectivorous 
birds  that  formerly  held  such  life  in  check. 

Caterpillars  often  cause  considerable  destruction 
to  forest  trees. 

The  caterpillar  of  the  pine  bombyx  often  causes 
great  ravages  in  the  pine  forests.  In  Germany 
these  caterpillars  are  called  pine-spinners,  from  the 
great  number  of  cocoons  with  which  they  cover 
the  pine-trees.  Such  caterpillars  have  been  known 
to  completely  destroy  extensive  pine  forests.  The 
foresters  are  often  compelled  to  set  fire  to  portions, 
of  the  forests  in  order  to  prevent  the  too  rapid 
multiplication  of  this  pest. 

Another  caterpillar,  which  from  its  black  and 
white  coating  is  sometimes  called  the  monk  or 
nun  caterpillar,  is  equally  destructive,  not  only  to 
forest  trees  like  the  pine,  but  also  the  other  forest 
trees,  such  as  the  beech,  oak,  and  birch. 

Other  caterpillars  cause  great  destruction  to  the 
forest  by  eating  the  tender  buds  or  the  young 
shoots. 

• 

Grasshoppers  often  cause  considerable  damage 
to  young  trees  by  devouring  the  leaves,  herbs,  and 
tender  shoots. 


THE  ANIMATE  ENEMIES  OF  THE  FOREST.      75 

The  larvae  of  insects  do  great  damage  to  trees 
by  boring  chambers,  or  tunnellings,  either  in 
the  heart-wood  or  in  the  layers  of  new  wood 
which  lie  directly  under  the  bark.  The  destruc- 
tive powers  of  such  larvae  are  the  more  marked, 
since  they  work  silently  and  in  the  dark,  and  their 
presence  can  scarcely  be  detected  until  they  have 
caused  the  death  of  the  tree. 

A  beetle  known  as  the  typographer  (Bostrychus 
typographicus\  from  the  shape  of  the  galleries  it 
burrows  out  in  the  trees,  causes  much  damage  to 
the  forests,  especially  to  the  spruce-firs.  Unfortu- 
nately, these  insects  breed  very  rapidly,  and  while 
in  the  larva  state  are  capable  of  withstanding  the 
most  severe  frosts. 

Some  species  of  willows  are  severely  injured  by 
the  larvae  of  a  species  of  saw-fly,  which  strip  the 
leaves  and  injure  the  tree  generally. 

Perhaps  the  best  remedy  for  the  ravages  of 
insects  in  general  is  to  be  found  in  the  preserva- 
tion of  insectivorous  birds. 

The  most  powerful  enemy  of  the  forest,  how- 
ever, is  civilized  man.  The  products  of  the  forest 
are  clearly  man's  right  by  gift  of  nature.  He  is 
lord  of  the  forest  as  of  the  rest  of  the  earth,  and 
is,  therefore,  entitled  to  the  use  of  the  wood  thus 


76  OUTLINES  OF  FORESTRY. 

grown  for  him.  It  is,  however,  by  the  abuse  and 
not  by  the  use  of  nature's  lavish  gifts  that  man 
deranges  its  economy,  and  thus  brings  on  himself 
so  much  punishment.  If  he  would  only  be  careful 
to  select  trees  of  vigorous  growth,  and  in  cutting 
them  down  would  exercise  care  that  the  remaining 
trees  might  live;  if  he  would  carefully  preserve 
the  soil,  and  hold  in  check  the  other  enemies  of 
the  forest ;  if  he  would  wisely  set  aside  large  por- 
tions of  the  mountain  slopes,  the  natural  home  of 
the  forest,  as  areas  on  which  trees  should  be  con- 
tinually preserved,  the  earth  would  yield  of  her 
abundance  all  the  wood  required  for  his  use. 

Referring  to  the  insect  enemies  of  the  forest, 
Hough,  in  a  report  to  the  United  States  Commis- 
sioners of  Agriculture,*  page  263,  in  citing  a 
writing  of  Grandjean,  Conservateur  des  Forets, 


"  The  timber-tree  particularly  suffering  from  this  cause  was 
the  Abies  excelsa  (D.C.),  or  common  European  spruce-fir,  and 
the  species  of  insects  that  did  the  injury  were  the  Bostrychus 
typographicus  and  the  B.  chalcographicus,  of  which  the  first 

*  Eeprinted,  by  permission,  from  the  "  Report  on  Forestry," 
submitted  to  Congress  by  the  Commissioner  of  Agriculture, 
by  Franklin  B.  Hough.  Washington :  Government  Printing- 
Office,  1882.  Pp.318. 


THE  ANIMATE  ENEMIES  OF  THE  FOREST.      77 

attacked  the  trunk  and  large  branches,  and  the  latter,  which 
was  seldom  absent,  found  a  lodgment  in  the  smaller  branches. 
Their  habits  were  described  as  follows : 

"  When  the  female  of  the  typographic  species  is  ready  to  de- 
posit her  eggs,  which  occurs  about  the  middle  or  latter  part  of 
spring,  sooner  or  later,  according  to  the  temperature,  she  pene- 
trates the  bark,  and  bores,  almost  invariably  from  below  up- 
wards, a  gallery  that  is  cut  along  the  outer  layer  of  the  sap- 
wood,  depositing  her  eggs,  as  she  advances,  on  the  right  side 
and  the  left.  These  are  so  quickly  developed  that  the  first 
larvae  will  have  themselves  made  considerable  galleries  before 
the  parent  has  finished.  Each  of  these  larvae  digs  a  separate 
path  of  its  own,  more  or  less  inclined  to  that  made  by  the 
mother,  and  at  the  end  of  two  or  two  and  a  half  months  they 
are  transformed  to  a  perfect  insect,  which  in  turn  proceeds  to 
lay  a  new  lot  of  eggs,  and,  if  favored  by  the  heat  of  August, 
these  are  sometimes  found  more  destructive  than  the  first. 
This  second  growth  is  matured  towards  the  end  of  September 
or  beginning  of  October,  and  will  be  ready  to  resume  opera- 
tions in  the  following  spring.  In  the  mean  time  they  pass  the 
winter  under  the  mosses  and  in  the  crevices  of  the  bark,  where 
they  endure  the  severest  frosts  of  winter,  for  the  perfect  insect 
is  as  hardy  as  its  larvae  are  tender. 

"  The  number  of  eggs  deposited  by  one  insect  varies  from 
twenty  to  one  hundred  and  twenty  or  one  hundred  and  thirty, 
and  from  this  bark  we  may  make  some  very  instructive  estimates. 
Suppose  that  each  laying  of  sixty  eggs  produces  specimens  in 
which  the  sexes  are  equal,  one  female  will  have  produced 
thirty  others,  which  would  each  before  the  end  of  the  year  be 
represented  by  eighteen  hundred  of  their  kind.  Half  of  these, 

7* 


78  OUTLINES  OF  FORESTRY. 

before  the  end  of  the  second  year,  have  produced  eight  hun- 
dred and  ten  thousand  females,  and  by  the  end  of  the  third 
year  seven  hundred  and  twenty-nine  millions  of  the  producing 
sex,  and  the  forest  will  have  fed  one  billion  five  hundred  and 
six  million  six  hundred  thousand  of  the  progeny  of  this  one 
parent." 

Concerning  the  destructive  effects  of  the  animal 
kingdom,  Geikie,  in  his  "  Text-Book  of  Geology,"* 
page  456,  writes : 

"Many  animals  exercise  a  ruinously  destructive  influence 
on  vegetation.  Of  the  various  insect  plagues  of  this  kind  it 
will  be  enough  to  enumerate  the  locust,  phylloxera,  and  Colo- 
rado beetle.  The  pasture  in  some  parts  of  the  south  of  Scot- 
land has,  in  recent  years,  been  damaged  by  mice,  which  have 
increased  in  numbers  owing  to  the  indiscriminate  shooting 
and  trapping  of  owls,  hawks,  and  other  predaceous  creatures. 
Grasshoppers  cause  the  destruction  of  vegetation  in  some  parts 
of  Wyoming  and  other  Western  Territories  of  the  United 
States.  The  way  in  which  animals  destroy  each  other,  often 
on  a  great  scale,  may  likewise  be  included  among  the  geologi- 
cal operations  now  under  description." 

Speaking  of  the  influence  of  certain  insects  in 
destroying  forests  from  over  extended  districts, 

*  Keprinted,  by  permission,  from  a  "  Text-Book  of  Geology," 
by  Archibald  Geikie,  LL.D.  London :  Macmillan  &  Co.,  1882. 
Pp.  971. 


THE  ANIMATE  ENEMIES  OF  THE  FOREST.       79 

Pouchet,  in  his  work  entitled  the  "  The  Universe, 
or  the  Infinitely  Great  and  the  Infinitely  Little,"  * 
page  218,  says : 

"  If,  when  the  warm  breath  of  spring  drives  away  the  rigor 
of  winter  and  renews  life  in  the  fields,  we  enter  one  of  the 
great  coniferous  woods  of  Germany,  we  are  astonished  at  the 
tumult  and  activity  which  prevail  in  lieu  of  the  silence  we 
went  there  to  seek.  Everything  is  in  movement. 

"  Groups  of  woodmen,  foresters,  and  overseers  move  about  by 
hundreds,  and  stretch  away  like  columns  of  skirmishers ;  it  is 
a  complete  army  in  the  field,  which  opens  out  wherever  there 
is  a  large  space,  and  of  which  the  wings  are  sometimes  lost  in 
the  windings  of  the  roads,  or  hidden  by  the  projection  of  some 
hillock.  This  mass  of  men  always  moves  in  order,  distributed 
in  troops  commanded  by  experienced  leaders.  They  are  all 
provided  with  long  weapons,  which,  at  a  distance,  might  be 
taken  for  lances. 

"  Or,  if  the  excursion  is  made  by  night,  another  spectacle 
awaits  us.  The  whole  forest  seems  on  fire.  In  every  part  are 
burning  great  trees,  erect  and  isolated,  like  huge  threatening 
torches,  the  flame  of  which  rises  to  the  clouds  and  casts  a 
baleful  glance  on  all  around.  A  few  foresters,  standing  in 
silence,  contemplate  the  progress  of  the  conflagration,  and 
watch  its  ravages.  Lastly,  at  other  times,  as  a  final  resource, 
the  entire  forest  is  given  up  a  prey  to  the  flames,  and  whirl- 

*  Reprinted,  by  permission,  from  "  The  Universe,  or  the 
Infinitely  Great  and  the  Infinitely  Little,"  by  F.  A.  Pouchet, 
M.D.  New  York :  Charles  Scribner  &  Co.,  1870.  Pp.  790. 


80  OUTLINES  OF  FORESTRY. 

winds  of  fire,  menacing  and  dreadful,  spread  on  every  side ;  a 
woody  region,  formerly  so  fertile,  is  entirely  devoured  by  fire, 
and  only  an  immense  mountain  of  charcoal  remains  of  all  this 
mass  of  wealth. 

"  We  ask,  against  what  formidable  enemy  such  an  army  of 
men  has  been  launched  ?  Who  are  they  going  to  attack  with 
their  rods  which  they  brandish  on  all  sides  ?  What  redoubta- 
ble aggressors  are  the  others  attempting  to  stay  the  march  of, 
with  the  long  trenches  they  are  scooping  out?  Why  these 
frightful  fires  in  the  middle  of  the  night  ?  Why  this  general 
conflagration  ?" 


THE  DESTRUCTION  OF  THE  FOREST.  81 


VIII.    THE   DESTRUCTION   OF  THE 
FOREST. 

THE  removal  of  the  forests  from  any  consider- 
able section  of  country,  in  the  end,  is  invariably 
followed  by  some  or  all  of  the  following  results : 

1.  An  increase  in  the  frequency  with  which  the 
rivers  in  that  section  of  country  overflow  or  inun- 
date their  banks. 

2.  An  increase  in  the  frequency  and  severity  of 
droughts,  as  witnessed  by  a  marked  decrease  in  the 
amount  of  water  in  the  river  channels,  and  by  an 
increase  in  the  frequency  with  which  the  springs, 
in  such  section  of  country,  either  show  a  marked 
decrease  in  their  flow  or  dry  up  altogether. 

3.  A  rapid  loss  of  the  soil  from  such  areas,  re- 
sulting from  the  more  rapid  surface  drainage  of 
their  surfaces. 

4.  A  marked  disturbance  in  the  lower  courses 
of  the  rivers,  rising  in  or  flowing  through  such 
section  of  country,  produced  by  the  filling  up  of 
their  channels  by  sand-bars  or  mud-flats. 


82  OUTLINES  OF  FORESTRY. 

5.  A  decrease  in  the  healthfullness  of  the  district 
that  borders  on  the  lower  courses  of  such  rivers, — 
that  is,  in  those  portions  which  lie  in  the  lowlands 
near  the  rivers'  mouths. 

6.  An  increase  in  the  number  and  severity  of 
hail-storms,  both  over  the  areas  themselves  or  in 
the  countries  bordering  thereon. 

"When  the  forests  are  removed  from  any  section 
of  country,  that  part  of  the  rainfall  which  for- 
merly entered  the  ground,  either  by  gradually 
sinking  into  the  porous  soil,  or  by  running  along 
the  branches  and  trunks  of  the  trees,  and  so  enter- 
ing and  penetrating  the  more  deeply-seated  strata, 
now  drains  rapidly  off  the  surface.  Instead  of 
reaching  the  river  channel  quietly  and  slowly 
through  discharge  from  the  reservoirs  of  springs, 
it  now  rapidly  drains  directly  off  the  surface  into 
the  river  channel. 

Instead  of  draining  into  the  river  channel  con- 
tinuously for  a  period  of,  say,  three  weeks,  the 
rain-water  now  drains  into  the  channel  in  often  a 
period  of  as  many  hours.  The  channel  rapidly 
fills,  the  river  overflows  its  banks,  and  the  floods  so 
caused  carry  loss  to  the  lowlands  along  the  river 
banks,  and,  not  infrequently,  death  to  the  inhabi- 
tants. 


THE  DESTRUCTION  OF  THE  FOREST.  83 

Not  only  are  the  riches  of  the  rainfall  thus 
squandered,  to  the  loss  of  the  inhabitants  of  the 
river  valleys,  from  the  excess  of  water  immediately 
after  a  rainfall,  but  a  still  greater  and  more  far 
reaching  loss  occurs  from  the  failure  of  the  rain- 
fall to  fill  the  reservoirs  of  the  springs,  the  contin- 
uous discharge  of  which  are  necessary  to  maintain 
the  proper  flow  of  water  in  the  river. 

The  springs,  having  their  reservoirs  but  partly 
filled,  are  apt  to  fail  shortly  after  the  rainfall 
ceases,  so  that  even  limited  droughts  may  cause 
them  to  dry  up  completely. 

The  damage,  however,  does  not  stop  here.  The 
soil  in  which  the  forest  grew,  being  no  longer  held 
together  either  by  the  roots  of  the  trees  or  under- 
brush of  the  forest,  or  protected  by  a  vegetable 
covering,  is  rapidly  carried  away  by  the  water. 
The  soil  thus  lost,  resulted  from  the  gradual  dis- 
integration of  hard  rocks,  and  contains  as  essen- 
tial elements  substances  derived  from  the  continued 
growth  of  former  generations  of  plants,  and  prob- 
ably required  centuries  for  its  production.  Its 
removal  in  a  few  years  is,  therefore,  a  serious 
matter. 

The  soil,  the  wealth  of  the  highlands,  is  now 
thrown  into  the  river  channel,  and  though  some 


84  OUTLINES  OF  FORESTRY. 

of  it  fertilizes  the  lowlands,  over  which  it  is  spread 
during  inundations,  yet  much  collects  in  sand-bars 
and  mud-flats  on  the  lower  courses  of  the  river. 
These  flats  work  injury  because : 

1.  They  hinder  navigation,  and  thus  interfere 
with  the  commerce  between  different  parts  of  the 
country. 

2.  They  become  sources  of  contamination  to  the 
air  of  the  lowlands,  by  breeding  miasmatic  and 
other  diseases. 

Besides  the  disturbances  thus  caused  to  the 
drainage  of  the  region  from  which  the  forest  has 
been  removed,  considerable  changes  are  brought 
about  in  the  rate  at  which  the  now  bare  soil  re- 
ceives the  heat  from  the  sun,  and  the  rapidity  with 
which  it  throws  it  off  into  the  air. 

Areas  covered  with  forests  both  receive  and  part 
with  their  heat  slowly,  and  are,  therefore,  not  very 
apt  to  become  very  hot  in  summer,  or  very  cold 
in  winter. 

Bare  areas,  or  areas  stripped  of  their  vegetable 
covering,  both  receive  and  part  with  their  heat 
rapidly,  and  are,  therefore,  apt  to  become  very  hot 
in  summer  and  very  cold  in  winter. 

The  presence  of  the  forest,  therefore,  tends  to 
prevent  marked  changes  in  the  temperature  of  the 


THE  DESTRUCTION  OF  THE  FOREST.  85 

air,  while  the  removal  of  the  forest  tends  to  permit 
Budden  changes  in  such  temperature. 

These  effects  will  be  considered  under  the  gen- 
eral head  of  climate. 

The  axe  of  the  pioneer,  so  often  regarded  as  the 
emblem  of  civilization,  is  more  correctly  to  be 
regarded  as  an  emblem  of  an  entirely  different 
character. 

The  problem  of  the  preservation  and  protection 
of  the  forest  is  one  of  extreme  difficulty,  for  the 
following  reasons : 

The  dense  populations  which  now  exist  in  most 
of  the  temperate  regions  of  the  earth  could  not 
continue  to  exist  in  the  forest  regions  which  once 
grew  on  large  parts  of  their  areas. 

The  regions  best  fitted  for  the  growth  of  men 
are  also  best  fitted  for  the  growth  of  trees.  Since 
civilized  man  cannot  continue  as  a  dweller  in  the 
forest,  as  the  density  of  population  increases,  the 
forest  must  be  cut  down. 

In  removing  the  forest  to  make  way  for  man, 
certain  areas  should  be  set  aside  in  all  sections 
for  the  purpose  of  perpetually  maintaining  trees 
thereon.  The  nature  of  such  areas  will,  of  course, 
depend  on  a  variety  of  circumstances.  In  general, 
however,  it  can  be  shown  that,  on  the  slopes  of 

8 


86  OUTLINES  OF  FORESTRY. 

mountain  ranges,  which  form  the  natural  places 
where  rivers  rise,  forests  should  be  especially 
maintained. 

Laws  should,  therefore,  be  enacted  providing  for 
the  replanting  of  trees  on  mountain  slopes,  either 
when  they  have  been  removed  by  the  axe  of  the 
woodman,  or  by  fire,  or  by  any  of  the  other 
enemies  of  the  forest. 

The  influence  of  the  destruction  of  the  forest 
on  the  rapidity  of  drainage,  and  the  consequent 
liability  to  the  destructive  floods,  is  thus  referred 
to  by  the  author  in  his  "  Elements  of  Physical 
Geography,"  *  page  64,  as  follows : 

"  Influence  of  the  Destruction  of  the  Forests  on  Inundations. — 
When  the  forests  are  removed  from  a  large  portion  of  a  river- 
basin,  the  rains  are  no  longer  absorbed  quietly  by  the  ground, 
but  drain  rapidly  off  its  surface  into  the  river  channels,  and 
thus  in  a  short  time  the  entire  precipitation  is  poured  into  the 
main  channel,  causing  an  overflow.  It  is  from  this  cause  that 
the  disastrous  effects  of  otherwise  harmless  storms  are  pro- 
duced. The  inundations  are  most  intensified  by  this  cause  in 
the  early  spring,  when  the  ice  and  snow  begin  to  melt.  The 
destructive  effects  of  the  floods  are  increased  by  the  masses  of 

*  Eeprinted,  by  permission,  from  "  The  Elements  of  Physi- 
cal Geography,"  by  Edwin  J.  Houston,  A.M.  Philadelphia : 
Eldredge  &  Brother,  No.  17  North  Seventh  Street,  1891.  Pp. 
172. 


THE  DESTRUCTION  OF  THE  FOREST.  87 

floating  ice,  which,  becoming  gorged  in  shallow  places  in  the 
stream,  back  up  the  waters  above.  The  increased  frequency 
of  inundations  in  the  United  States  is,  to  a  great  extent,  to  be 
attributed  to  the  rapid  destruction  of  the  forests." 

Sir  Charles  Lyell,  in  his  "Principles  of  Ge- 
ology," *  speaking  of  the  effects  produced  by  the 
removal  of  the  forest,  says,  on  page  457 : 

"  When  St.  Helena  was  discovered,  about  the  year  1506,  it 
was  entirely  covered  with  forests,  the  trees  drooping  over  the 
tremendous  precipices  that  overhang  the  sea.  Now,  says  Dr. 
Hooker,  all  is  changed ;  fully  five-sixths  of  the  island  is  en- 
tirely barren,  and  by  far  the  greater  part  of  the  vegetation 
that  exists,  whether  herbs,  shrubs,  or  trees,  consists  of  intro- 
duced European,  American,  African,  and  Australian  plants, 
which  propagated  themselves  with  such  rapidity  that  the  na- 
tive plants  could  not  compete  with  them.  These  exotic  species, 
together  with  the  goats,  which,  being  carried  to  the  island,  de- 
stroyed the  forests  by  devouring  all  the  young  plants,  are  sup- 
posed to  have  utterly  annihilated  about  one  hundred  peculiar 
and  indigenous  species,  all  record  of  which  is  lost  to  science, 
except  those  of  which  specimens  were  collected  by  the  late 
Dr.  Burchell,  and  are  now  in  the  herbarium  of  Kew." 

The  protective  action  or  plants  generally  as  pre- 
venting erosion  by  water  or  wind  is  clearly  pointed 

*"  Principles  of  Geology,"  by  Sir  Charles  Lyell,  M.A. 
London  :  John  Murray,  1872.  Pp.  652. 


88  OUTLINES  OF  FORESTRY. 

out  by  Geikie,  in  his  "  Text-Book  of  Geology,"  * 
on  page  456. 

"  The  protective  influence  of  vegetation  is  well  known. 

"  1.  The  formation  of  a  stratum  of  turf  protects  soil  and  rocks 
from  being  rapidly  removed  by  rain  or  wind.  Hence,  the 
surface  of  a  district  so  protected  is  denuded  with  extreme 
slowness  except  along  the  lines  of  its  water- courses. 

"  2.  Many  plants,  even  without  forming  a  layer  of  turf,  serve 
by  their  roots  or  branches  to  protect  the  loose  sand  or  soil  on 
which  they  grow  from  being  removed  by  wind.  The  common 
sand-carex  and  other  arenaceous  plants  bind  littoral  sand- 
dunes  and  give  them  a  permanence  which  would  at  once  be 
destroyed  were  the  sand  laid  bare  again  to  storms.  In  North 
America  the  sandy  tracts  of  the  Western  Territories  are  in 
many  places  protected  by  the  sage-brush  and  grease-wood. 
The  growth  of  shrubs  and  brushwood  along  the  course  of  a 
stream  not  only  keeps  the  alluvial  banks  from  being  so  easily 
undermined  and  removed  as  would  otherwise  be  the  case,  but 
serves  to  arrest  the  sediment  in  floods,  filtering  the  water  and 
thereby  adding  to  the  height  of  the  flood-plain.  On  some  parts 
of  the  west  coast  of  France  extensive  ranges  of  sand-hills  have 
been  gradually  planted  with  pine  woods,  which,  while  prevent- 
ing the  destructive  inland  march  of  the  sand,  also  yield  a  large 
revenue  in  timber,  and  have  so  influenced  the  climate  as  to 
make  these  districts  a  resort  for  pulmonary  invalids.  In  tropi- 

*  Reprinted,  by  permission,  from  a  "  Text-Book  of  Geology," 
by  Archibald  Geikie,  LL.D.  London :  Macmillan  &  Co.,  1882. 
Pp.  971. 


THE  DESTRUCTION  OF  THE  FOREST.  89 

cal  countries  the  mangrove  grows  along  the  sea-margin,  and 
not  only  protects  the  land,  but  adds  to  its  breadth,  by  forming 
and  increasing  a  maritime  alluvial  belt." 

The  following,  from  the  "  Journal  of  the  Society 
of  Arts,"  *  shows  the  enormous  demands  made  on 
the  forest  by  railroads  for  sleepers  : 

"  The  Belgian  '  Bulletin  du  Muse"e  Commercial'  gives  the 
following  information  respecting  the  number  of  sleepers  used 
on  various  railways.  In  France  alone  the  six  larger  railway 
companies  require  a  daily  supply  of  more  than  ten  thousand 
sleepers,  making  an  annual  consumption  of  over  three  million 
six  hundred  and  fifty  thousand.  As  a  tree  of  ordinary  di- 
mensions cannot  furnish  more  than  ten  logs,  it  follows  that 
more  than  a  thousand  fine  trees  are  cut  down  every  day  solely 
for  the  purpose  of  supplying  the  necessary  sleepers  for  the 
French  railways.  In  the  United  States  the  amount  required 
is  still  greater.  Over  fifteen  million  sleepers  are  annually 
used  in  this  country,  thus  necessitating  the  annual  destruction 
of  eighty  thousand  hectares,  or  one  hundred  and  ninety-seven 
thousand  six  hundred  acres  of  forests.  'The  Bulletin  du 
Musee  Commercial'  estimates  at  more  than  forty  millions  the 
number  of  logs  required  for  the  railways  of  the  world,  and  is 
of  opinion  that  the  estimate  is  rather  below  than  above  the 
mark." 

*  "  Journal  of  the  Society  of  Arts,"  vol.  xxvii.  London : 
George  Bell  &  Sons,  6  York  Street,  Covent  Garden,  1889. 
Pp.  924. 

8* 


90  OUTLINES  OF  FORESTRY. 


IX.  THE  EARTH'S  OCEAN  OF  VAPOR. 

FROM  every  water  surface  on  the  earth  there  is 
almost  constantly  rising  and  passing  into  the  air 
an  invisible  form  of  water  called  vapor. 

Yapor  is  formed  wherever  water  is  sufficiently 
heated  under  such  circumstances  that  its  particles 
have  freedom  to  expand,  and  thus  occupy  a  greater 
space. 

The  waters  of  the  earth  are  caused  to  pass  into 
the  atmosphere  as  vapor  mainly  by  the  heat  of  the 
sun. 

The  vapor  that  passes  into  the  air  from  the 
ocean  and  other  water  surfaces  spreads  or  diffuses 
through  the  air,  and  is  carried  by  the  winds  to 
different  parts  of  the  earth's  surface.  The  air  di- 
rectly over  a  water  surface  is,  however,  generally 
moister  than  that  over  a  land  surface. 

When,  by  any  cause,  water  vapor  loses  the  heat 
which  caused  it  to  become  a  vapor,  it  again  be- 
comes visible  as  dew,  fog,  cloud,  or  mist,  or  falls 
as  rain,  hail,  or  snow. 

The  rapidity  with  which  water  surfaces  throw 


THE  EARTH'S  OCEAN  OF  VAPOR.  91 

off  vapor  into  the  air  varies  with  the  following 
circumstances : 

1.  "With  the  amount  of  surface  exposed. 
Evaporation  takes  place  only  at  the  surface; 

consequently,  the  greater  the  surface,  the  greater 
the  rapidity  of  evaporation.  When  wet  clothes 
are  hung  out  to  dry,  they  are  so  opened  or  spread 
out  that  the  air  can  act  on  them  from  all  sides. 
A  pound  of  water  placed  in  an  open  shallow  dish, 
and  exposed  to  the  air,  will  evaporate  much  more 
rapidly  than  the  same  quantity  would  if  placed  in 
an  open,  narrow-necked  bottle. 

For  the  same  reason,  an  equal  quantity  of  water 
will  evaporate  still  more  rapidly  when  sprinkled  on 
the  surface  of  a  sheet  hung  out  in  the  air  to  dry. 

2.  On  the  temperature  of  the  air. 

The  capacity  of  a  given  volume  of  air  for 
water  in  a  state  of  vapor  rapidly  increases  with 
its  temperature.  A  cubic  foot  of  dry  air  at  the 
temperature  of  melting  ice,  or  32  degrees  Fahren- 
heit, when  saturated,  holds  a  little  more  than  half 
a  grain  of  vapor.  It  then  being  saturated  can 
hold  no  more  water  in  an  invisible  state.  In- 
crease its  temperature,  however,  to  212  degrees 
Fahrenheit,  and  it  can  hold  twenty  grains,  or 
about  forty  times  as  much  as  it  formerly  held. 


92  OUTLINES  OF  FORESTRY. 

Consequently,  any  increase  in  the  temperature 
of  air  permits  it  to  hold  a  greater  quantity  of 
vapor.  Conversely,  any  decrease  in  the  tempera- 
ture of  air  causes  its  ability  to  hold  moisture  as 
vapor  to  decrease. 

If,  therefore,  the  temperature  of  the  air  be  suffi- 
ciently decreased,  a  part  of  the  vapor  it  contains 
will  appear  in  some  visible  form. 

3.  On  the  quantity  of  vapor  already  in  the  air. 
When  a  given  bulk  of  air  has  as  much  vapor  in 

it  as  it  can  hold,  all  evaporation  ceases.  Conse- 
quently, the  drier  the  air  over  a  water  surface,  the 
greater  is  the  rapidity  of  evaporation. 

4.  On  the  velocity  of  the  wind. 

The  wind  brings  fresh  and  drier  air  to  the 
water  surfaces,  and  at  the  same  time  removes  the 
air  into  which  such  surfaces  were  discharging 
their  vapor.  An  increase  in  the  velocity  of  the 
wind,  therefore,  increases  the  rapidity  of  evapora- 
tion. 

5.  On  the  pressure  of  the  air. 

The  greater  pressure  the  air  exerts  on  a  water 
surface,  the  slower  the  rapidity  of  evaporation.  A 
low  barometer  permits  a  water  surface  to  throw  off 
its  vapor  with  much  greater  rapidity  than  a  high 
barometer. 


THE  EARTHS  OCEAN  OF  VAPOR.  93 

When  clouds  reach  the  higher  regions  of  the 
atmosphere  they  disappear,  because  the  particles 
of  water  of  which  they  are  composed  pass  rapidly 
into  an  invisible  vapor,  on  account  of  the  great 
relief  of  pressure  in  the  higher  regions. 

The  earth's  ocean  of  vapor  is  of  the  greatest 
importance  to  its  present  race  of  animals  and 
plants.  If  any  considerable  change  in  either  the 
quantity  or  distribution  of  vapor  should  be  main- 
tained for  any  considerable  time,  the  present  race 
of  animals  and  plants  would  disappear. 

Some  of  the  more  important  ways  in  which  the 
ocean  of  vapor  affects  the  economy  of  the  earth 
are  as  follows : 

1.  By  the  action  of  the  winds,  the  water  vapor 
is  carried  from  the  warm  regions  of  the  earth  to 
the  colder  regions,  where,  falling  as  rain  or  snow, 
it  gives  out  its  heat  and  raises  the  temperature  of 
the  air  over  such  regions. 

An  interchange  is  thus  effected  between  the  too 
great  heat  of  the  equatorial  regions  and  the  too 
feeble  heat  of  the  poles,  and  a  more  equable,  uni- 
form temperature  is  insured  than  would  otherwise 
exist. 

The  earth's  ocean  of  vapor  therefore  acts  to 
moderate  the  excessive  temperatures  that  would 


94  OUTLINES  OF  FORESTRY. 

otherwise  exist  both  in  the  equatorial  and  in  the 
polar  regions. 

2.  By  acting  as  a  screen  interposed  between  the 
earth  and  the  sun,  and  thus  preventing  the  earth's 
surface  from  becoming  too  rapidly  heated  when 
exposed  to  the  sun's  rays,  or  too  rapidly  cooled 
when  deprived  of  such  rays. 

"Water  enters  so  largely  into  the  composition  of 
both  animals  and  plants,  that  its  absence  from  any 
section  of  country  invariably  causes  such  section 
to  become  a  desert. 

"Within  certain  limits,  the  wealth  of  any  section 
of  country  can  be  accurately  estimated  by  the 
number  of  inches  of  rain  that  fall  in  a  given  time 
on  its  surface.  This  liquid  wealth  may  be  regarded 
as  a  species  of  bank  account  of  such  section  of 
country,  by  which  its  solvency  or  bankruptcy  may 
be  determined. 

The  ocean  of  vapor  which  forms  the  source  from 
which  the  rains  are  derived  is,  therefore,  of  great 
importance  to  the  operations  of  nature. 

Even  a  hurried  glance  at  the  map  of  the  world 
will  show  that  the  earth's  greatest  expanse  of  water 
surface  occurs  near  the  equatorial  regions.  Here, 
also,  the  sun's  heat  is  greatest.  The  air  over  the 
equatorial  regions  would  become  too  enormously 


THE  EARTH'S  OCEAN  OF  VAPOR.  95 

heated  to  sustain  the  present  life  of  the  earth,  were 
the  water  surfaces  replaced  hy  land. 

Not  only  does  a  water  surface  heat  more  rapidly 
than  a  land  surface,  but  the  vapor  which  arises 
from  it,  locks  up  much  of  the  heat  in  a  form  that 
is  sometimes  popularly  called  latent  heat. 

To  change  a  pound  of  ice,  at  thirty-two  degrees 
Fahrenheit,  into  a  pound  of  water,  at  thirty-two 
degrees  Fahrenheit,  requires  one  hundred  and 
forty-two  heat  units,  or  one  hundred  and  forty- 
two  times  as  much  heat  as  is  required  to  raise 
the  temperature  of  a  pound  of  water  one  degree 
Fahrenheit.  To  convert  one  pound  of  water  at 
sixty  degrees  Fahrenheit  into  vapor  requires  nearly 
one  thousand  heat  units,  an  amount  of  heat  that 
would  be  able  to  raise  more  than  six  pounds  of 
ice-cold  water  to  the  temperature  of  its  boiling- 
point.  When  the  vapor  is  condensed  and  falls  as 
rain  or  snow,  this  heat  reappears  and  raises  the 
temperature  of  the  air.  When,  therefore,  the  ex- 
cessive heat  of  the  sun  in  the  equatorial  regions 
falls  on  the  extended  water  surfaces,  much  of  the 
heat  is  absorbed  by  the  vapor,  and  the  air  is  pre- 
vented from  growing  too  hot.  This  vapor  is  car- 
ried by  the  winds  to  the  polar  regions,  where  it 
gives  up  its  heat  to  the  air,  and  falls  as  rain  or  snow. 


96  OUTLINES  OF  FORESTRY. 

The  vapor  of  water  exerts  another  and  still 
more  powerful  influence  on  the  climate  of  the 
earth.  Water  vapor  possesses  in  a  marked  de- 
gree the  power  of  absorbing  heat  rays  of  the  sun. 
About  twenty-eight  per  cent,  of  the  heat  of  the 
vertical  rays  is  absorbed  before  such  rays  reach 
the  surface,  provided  there  is  a  sufficient  quantity 
of  vapor  in  the  air.  "When  the  heated  earth  throws 
off  or  radiates  its  heat  into  the  atmosphere,  the 
same  water  vapor  absorbs  a  greater  part  of  such 
rays,  and  rapid  cooling  by  radiation  is  thus  pre- 
vented. The  presence  of  the  water  vapor,  there- 
fore, prevents  either  the  rapid  heating  of  the 
earth's  surface  by  the  direct  action  of  the  sun's 
rays,  or  the  rapid  cooling  of  such  surface  by 
radiation. 

If  the  earth's  surface  were  deprived  of  this 
screen  of  vapor,  the  air  would  become  so  rapidly 
heated  on  the  rising  of  the  sun,  and  so  rapidly 
cooled  on  its  setting,  that  the  earth  would  be 
unable  to  sustain  its  present  plant  and  animal 
life. 

Tyndall,  speaking  of  the  influence  that  the 
earth's  water  vapor  exerts  on  the  climate  of  Eng- 
land, says,  "  The  removal  for  a  single  summer 
night  of  the  clouds  of  vapor  which  cover  Eng- 


THE  EARTH'S  OCEAN  OF  VAPOR.  97 

land  would  be  attended  by  the  destruction  of 
every  plant  which  a  freezing  temperature  could 
kill." 

The  amount  of  vapor  in  the  air  of  any  country, 
though  dependent  on  the  direction  from  which  the 
winds  come,  is  also  markedly  influenced  by  the 
nature  of  its  surface. 

The  presence  of  forests  over  any  section  of 
country  has  the  effect  of  decreasing  the  rapidity 
with  which  the  wet  surface  parts  with  or  loses  its 
water  by  evaporation.  This  decrease  in  the  rapid- 
ity of  evaporation  is  caused  : 

(a.)  Because  the  air  over  the  forest  is  generally 
moister  than  that  over  the  open  fields,  and  evapo- 
ration takes  place  less  rapidly  in  moist  air. 

(b.)  Because  the  ground  in  the  forest  is  shielded 
from  the  direct  rays  of  the  sun. 

(c.)  Because  the  wet  ground  is  protected  from 
the  direct  action  of  the  wind. 

The  presence  of  the  forest,  therefore,  tends  to 
keep  the  air  moist  for  a  longer  time,  and  to  thus 
prevent  the  occurrence  of  marked  contrasts  in  the 
humidity  of  the  air. 

Some  experiments  made  in  France  show  that 
the  rapidity  of  evaporation  is  sixty-three  per  cent, 
less  in  the  forest  than  in  the  open  fields. 

«        9  9 


98  OUTLINES  OF  FORESTRY. 

The  influence  of  the  vapor  screen  that  is  placed 
between  any  surface  and  the  sun  on  the  climate  of 
the  surface  is  thus  referred  to  by  Tyndall  in  his 
"  Heat  as  a  Mode  of  Motion,"  *  on  page  417  : 

"  A  few  years  ago  a  work  possessing  great  charms  of  style 
and  ingenuity  of  reasoning  was  written  to  prove  that  the  more 
distant  planets  of  our  system  were  uninhabitable.  Applying 
the  law  of  inverse  squares  to  their  distances  from  the  sun,  the 
diminution  of  temperature  was  found  to  be  so  great  as  to  pre- 
clude the  possibility  of  human  life  in  the  more  remote  mem- 
bers of  the  solar  system.  But  in  those  calculations  the  influ- 
ence of  an  atmospheric  envelope  was  overlooked,  and  this 
omission  vitiated  the  entire  argument.  An  atmosphere  may 
act  the  part  of  a  barb  to  the  solar  rays,  permitting  them  to 
reach  the  earth,  but  preventing  their  escape.  A  layer  of  air 
two  inches  in  thickness,  saturated  with  the  vapor  of  sulphuric 
ether,  would  offer  very  little  resistance  to  the  passage  of  the 
solar  rays,  but  I  find  that  it  would  cut  off  fully  thirty-five  per 
cent,  of  the  planetary  radiation.  It  would  require  no  inor- 
dinate thickening  of  the  layer  of  vapor  to  double  this  ab- 
sorption ;  and  it  is  perfectly  evident  that,  with  a  protecting 
envelope  of  this  kind,  permitting  the  heat  to  enter,  but 
preventing  its  escape,  a  comfortable  temperature  might  be 
obtained  on  the  surface  of  the  most  distant  planet." 

*  Eeprinted,  by  permission,  from  "  Heat  as  a  Mode  of  Mo- 
tion," by  John  Tyndall,  LL.D.,  F.K.S.  New  York :  Appleton 
and  Company,  1883.  Pp.  591. 


THE  EARTH'S  OCEAN  OF  VAPOR.  99 

Alexander  von  Humboldt,  in  his  "  Cosmos,"  * 
thus  refers  to  the  vapor  of  the  atmosphere,  on 
page  330,  of  vol.  i. : 

"  As  the  quantity  of  moisture  in  the  atmosphere  increases 
with  the  temperature,  this  element,  so  important  to  the  whole 
organic  creation,  varies  with  the  hour  of  the  day,  the  season 
of  the  year,  and  the  degree  of  latitude  and  of  elevation.  Our 
knowledge  of  the  hygrometric  relations  of  the  atmosphere  has 
been  materially  augmented  of  late  years  by  the  method  now 
so  generally  and  extensively  employed  of  determining  the 
relative  quantity  of  vapor,  or  the  conditions  of  moisture  of 
the  atmosphere,  by  means  of  the  difference  of  the  dew  point 
and  of  the  temperature  of  the  air,  according  to  the  ideas  of 
Daniell  and  of  Dalton,  and  by  the  use  of  the  wet-bulb  ther- 
mometer. Temperature,  atmospheric  pressure,  and  the  di- 
rection of  the  wind  have  all  a  most  intimate  relation  to  the 
atmospheric  moisture  so  essential  to  organic  life.  The  influ- 
ence, however,  of  humidity  on  organic  life  is  less  a  con- 
sequence of  the  quantity  of  vapor  held  in  solution  under 
different  zones  than  the  nature  and  frequency  of  the  aqueous 
precipitations  which  refresh  the  ground  in  the  form  of  dew, 
mist,  rain,  or  snow." 

*  "  Cosmos,"  vol.  i.,  by  Alexander  von  Humboldt.  Lon- 
don :  Longman,  Brown,  Green  &  Longmans,  1849.  Pp.  487. 


100  OUTLINES  OF  FORESTRY. 


X.  RAIN. 

THE  vapor  which  rises  from  the  surface  of  the 
ocean,  and,  indeed,  from  all  water  surfaces,  mixes 
or  diffuses  through  the  air,  and  is  carried  by  the 
winds  to  different  parts  of  the  earth.  The  air  over 
parts  of  the  earth  at  considerable  distances  from 
any  large  body  of  water  may  therefore  contain 
much  vapor. 

The  quantity  of  water  the  air  can  hold,  in  an 
invisible  state  as  vapor,  increases  rapidly  with  an 
increase  in  the  temperature.  Consequently,  when 
air  containing  vapor  is  considerably  chilled,  it  can 
no  longer  hold  as  much  as  it  formerly  did,  and  a 
part  appears  as  rain,  or  as  some  other  form  of  pre- 
cipitation, such  as  dew,  snow,  hail,  fog,  cloud,  etc. 

The  amount  of  water  that  falls,  or  is  precipitated 
from  the  air,  depends  not  only  on  the  quantity  of 
air  that  is  chilled,  and  on  the  extent  of  this  chill- 
ing, but  also  on  the  quantity  of  moisture  the  air 
contained  before  it  was  chilled. 

The  lowering  of  temperature  necessary  to  pro- 
duce rain  may  be  caused  in  the  following  ways : 


RAIN.  101 

1.  The  moist  air  may  blow  along  the  earth's 
surface  towards  colder  regions. 

2.  The  moist  air  may  rise   directly  from  the 
earth's  surface  into  the  higher  and  colder  regions 
of  the  air. 

As  a  rule,  the  moist  air  which  blows  along  the 
earth's  surface  towards  the  poles  becomes  chilled 
and  deposits  its  moisture  as  rain  or  snow.  On  the 
contrary,  the  moist  air  which  blows  along  the 
earth's  surface  towards  the  equator  becomes,  for 
the  greater  part,  warmer  and,  thus,  becoming 
drier  takes  rather  than  gives  moisture,  and  pro- 
duces drought. 

Therefore,  as  a  rule,  only  the  surface  winds 
which  blow  towards  the  colder  regions  of  the 
earth  can  be  expected  to  bring  rain. 

In  the  tropical  regions,  however,  any  wind, 
whether  from  the  equator  or  from  the  poles,  which 
has  crossed  the  ocean  or  any  other  large  body  of 
water,  and  has  thereby  become  saturated  with 
moisture,  will  deposit  some  of  its  moisture  as  rain 
when  it  strikes  the  cooler  coasts  of  a  continent  or 
island.  Even  in  such  cases,  however,  the  equa- 
torial winds  are  more  apt  to  cause  heavy  rainfalls 
than  those  from  the  poles. 

A  warm,  moist  air,  when  sufficiently  chilled,  will 
9* 


102  OUTLINES  OF  FORESTRY. 

cause  a  heavier  rainfall  than  a  cold,  moist  air,  be- 
cause the  warm  air  has  a  greater  capacity  for  hold- 
ing vapor. 

In  general,  the  air  of  the  equatorial  zones  of  the 
earth  is  both  warmer  and  moister  than  that  of  the 
temperate  zones,  and  the  air  of  the  temperate  zones 
is  both  warmer  and  moister  than  that  of  the  polar 
zones. 

Consequently  the  rainfall  is  heaviest  in  the  equa- 
torial zones,  and  is  greater  in  the  temperate  zones 
than  in  the  polar  zones. 

The  air  near  the  coast  of  a  continent  or  island  is 
moister  than  that  over  the  interior.  Consequently 
the  rainfall  is  heavier  on  the  coasts  than  in  the 
interior. 

When  the  earth's  surface  is  intensely  heated,  the 
air  over  it  becomes  so  hot  that  it  rises  far  above  the 
surface.  If  sufficiently  moist,  the  chilling  so  caused 
produces  a  heavy  rainfall.  Much  of  the  rain  in 
the  tropical  regions  is  caused  in  this  manner. 

Mountains  form  excellent  means  for  cooling  the 
air  and  causing  its  invisible  water  or  vapor  to  fall 
as  rain.  They  act  no  matter  from  what  direction 
the  wind  may  be  blowing. 

"When  the  wind  blows  against  the  sides  or  slopes 
of  a  mountain,  it  is  forced  by  the  pressure  of  the 


RAIN.  103 

wind  behind  it  to  slowly  creep  up  the  slopes  of  the 
mountain,  and  becomes  chilled  in  the  colder  re- 
gions which  lie  near  the  summit.  If  this  lowering 
of  temperature  be  sufficiently  great,  the  moisture 
will  be  precipitated  from  the  air,  no  matter  from 
what  direction  the  wind  may  come. 

Mountains  may,  therefore,  cause  rain  to  fall 
from  any  wind  that  is  forced  to  blow  over  them, 
provided  they  are  sufficiently  high  to  cause  the 
necessary  amount  of  cooling.  When  a  mountain 
reaches  sufficiently  far  upward  into  the  air  to  cause 
the  temperature  to  fall  below  the  freezing-point 
of  water,  the  condensed  moisture  falls  as  snow. 

The  reason  so  many  rivers  rise  in  mountains  is 
to  be  found  in  the  fact  that  the  mountains  act  to 
chill  the  winds,  and  so  rob  the  air  of  its  moisture, 
no  matter  in  from  what  direction  the  wind,  which 
is  forced  to  ascend  their  slopes,  may  happen  to 
blow. 

Nearly  all  the  rivers  of  the  world  rise  in  moun- 
tainous districts.  4-8  a  rule,  the  largest  rivers  of 
the  world  rise  in  the  highest  mountains.  This  is 
because  the  higher  the  mountain  the  colder  its 
slopes,  the  cold  mountain  slopes  acting,  as  ex- 
plained, to  deprive  the  air  of  its  moisture. 

The  rain  that  falls  on  a  mountain's  slopes,  like 


104  OUTLINES  OF  FORESTRY. 

that  which  falls  on  any  other  part  of  the  earth's 
surface,  either  runs  rapidly  off  the  surface  or 
sinks  slowly  into  the  ground. 

The  part  that  runs  directly  off  the  ground  will 
be  greater  than  the  part  which  sinks  into  the 
ground,  when  the  surface  is  bare  and  devoid  of 
vegetation.  On  the  contrary,  the  part  which  sinks 
into  the  ground  will  be  greater  than  the  part  which 
runs  directly  oft'  the  surface,  when  the  surface  is 
covered  by  forests.  But  the  proportion  of  the 
rainfall  which  sinks  into  the  ground,  as  compared 
with  that  which  runs  directly  off  the  surface,  is 
greater  where  the  sides  of  mountains  are  covered 
with  forests  than  in  any  other  case. 

Since  the  rivers  which  rise  in  the  mountains  are 
more  regularly  fed  by  the  springs  when  the  greater 
part  of  the  rainfall  sinks  quietly  into  the  ground, 
and  since  this  occurs  on  mountains  that  are 
covered  with  trees,  the  importance  of  keeping  the 
sides  of  the  mountains  well  wooded  is  evident. 

"When  the  sides  of  mountains  are  covered  with 
forests,  the  rivers  that  rise  on  their  slopes  are  not 
only  less  apt  to  overflow  their  banks  during  heavy 
rainfalls,  but  are  also  less  apt  to  dry  up  and  be- 
come shallow  during  droughts,  than  if  such  forests 
were  removed. 


RAIN.  105 

The  forests  should,  therefore,  be  preserved  on  the 
mountain-sides,  in  order  to  protect  the  lowlands 
either  from  inundations  or  floods,  or  from  the 
effects  of  too  small  a  quantity  of  water  in  the 
rivers  which  flow  through  them  during  droughts. 

The  action  of  mountains  in  cooling  the  air  and 
causing  the  condensation  of  the  moisture  of  the 
air,  is  thus  referred  to  by  Tyndall  in  his  "  Heat  as 
a  Mode  of  Motion,"  *  page  384 : 

"  Mountains  act  as  condensers,  partly  by  the  coldness  of 
their  own  masses,  which  they  owe  to  their  elevation.  Above 
them  spreads  no  vapor  screens  of  sufficient  density  to  intercept 
their  heat,  which,  consequently,  passes  unrequited  into  space. 
When  the  sun  is  withdrawn,  this  loss  is  shown  by  the  quick 
descent  of  the  thermometer.  The  difference  between  a  ther- 
mometer which,  properly  protected,  gives  the  true  tempera- 
ture of  the  night-air,  and  one  which  is  permitted  to  radiate 
freely  towards  space,  must  be  greater  at  high  elevations  than 
at  low  ones.  This  conclusion  is  confirmed  by  observation. 
On  the  Grand  Plateau  of  Mont  Blanc,  for  example,  MM. 
Martins  and  Bravais  found  the  difference  between  two  such 
thermometers  to  be  twenty-four  degrees  Fahrenheit,  when 
a  difference  of  only  ten  degrees  was  observed  at  Chamouni." 


*  Keprinted,  by  permission,  from  "  Heat  as  a  Mode  of  Mo- 
tion," by  John  Tyndall,  LL.D.,  F.R.S.  New  York :  D.  Apple- 
ton  &  Co.,  1883.  Pp.591. 


106  OUTLINES  OF  FORESTRY. 

Huxley,  in  his  "  Physiography,"  *  speaks  as 
follows,  concerning  the  formation  of  rain,  on  page 
47: 

"  In  examining  the  distribution  of  rain,  it  will  be  found  to 
be  regulated  partly  by  the  physical  features  of  the  country, 
and  partly  by  the  character  of  the  prevailing  winds.  In  the 
neighborhood  of  mountains,  the  rainfall  is  increased,  since,  as 
has  already  been  pointed  out,  a  mass  of  moist  air,  when  forced 
up  the  side  of  a  mountain,  is  chilled  in  the  ascent,  and  its 
moisture  consequently  discharged.  Among  our  western  coun- 
ties, in  the  neighborhood  of  hills,  the  rainfall  rises  to  eighty, 
or  even  to  a  hundred,  inches,  and  upwards ;  while  away  from 
hills,  though  still  in  the  west,  it  is  only  from  thirty  to  forty- 
five  inches.  A  table-land,  or  high  plain  surrounded  by  moun- 
tains, will  generally  receive  but  little  rain,  since  the  winds 
which  reach  it  have  been  more  or  less  drained  of  moisture  in 
sweeping  over  the  surrounding  hills.  For  a  like  reason,  but 
little  rain  is  likely  to  fall  on  the  lee  side  of  a  high  hill,  and 
many  mountains,  consequently,  have  a  wet  and  a  dry  side ; 
the  wet  side  being,  of  course,  that  towards  which  the  predomi- 
nant winds  blow.  As  regards  the  influence  of  winds  on  rain, 
it  is  evident  that,  when  air  has  blown  over  a  large  expanse  of 
warm  water,  it  must  have  become  laden  with  moisture,  which 
will  be  readily  precipitated  on  exposure  to  refrigerating  influ- 
ences. Hence,  as  in  Britain,  so  in  the  greater  part  of  Europe, 
the  southerly  and  westerly  winds  bring  rain ;  and  most  rain 

*  Eeprinted,  by  permission,  from  "  Physiography,"  by  T.  H. 
Huxley,  F.R.S.  London :  Macmillan  &  Co.,  1883.  Pp.  384. 


RAIN.  107 

falls  in  the  exposed  westerly  parts,  such  as  the  coast  of  Portu- 
gal, Spain,  France,  Britain,  and  Norway.  There  are  certain 
conditions,  however,  under  which  rain  is  brought  to  our  islands 
by  easterly  rather  than  westerly  winds." 

Maury,  in  his  "  Physical  Geography  of  the 
Sea,"  *  on  page  120,  says  : 

"  We  shall  now  be  enabled  to  determine,  if  the  views  which 
I  have  been  endeavoring  to  present  be  correct,  what  parts  of 
the  earth  are  subject  to  the  greatest  fall  of  rain.  They  should 
be  on  the  slopes  of  those  mountains  which  the  trade-winds  or 
monsoons  first  strike  after  having  blown  across  the  greatest 
tract  of  ocean.  The  more  abrupt  the  elevation,  and  the  shorter 
the  distance  between  the  mountain-top  and  the  ocean,  the 
greater  the  amount  of  precipitation.  If,  therefore,  we  com- 
mence at  the  parallel  of  about  thirty  degrees  north  in  the  Pa- 
cific, where  the  northeast  trade-winds  first  strike  that  ocean,  and 
trace  them  through  their  circuits  till  they  meet  high  land,  we 
ought  to  find  such  a  place  of  heavy  rains.  Commencing  at 
this  parallel  of  thirty  degrees,  therefore,  in  the  North  Pacific, 
and  tracing  thence  the  course  of  the  northeast  trade- winds, 
we  shall  find  that  they  blow  thence,  and  reach  the  region  of 
equatorial  calms  near  the  Caroline  Islands.  Here  they  rise 
up ;  but,  instead  of  pursuing  the  same  course  in  the  upper 

*  Reprinted,  by  permission,  from  "  The  Physical  Geography 
of  the  Sea,  and  its  Meteorology,"  by  M.  F.  Maury,  LL.D., 
U.S.N.  New  York :  Harper  &  Brothers,  Publishers,  Franklin 
Square. 


108  OUTLINES  OF  FORESTRY 

stratum  of  winds  through  the  southern  hemisphere,  they,  in 
consequence  of  thet  rotation  of  the  earth,  are  made  to  take  a 
southeast  course.  They  keep  in  this  upper  stratum  until  they 
reach  the  calms  of  Capricorn,  between  the  parallels  of  thirty 
degrees  and  forty  degrees,  after  which  they  become  the  pre- 
vailing northwest  winds  of  the  southern  hemisphere,  which 
correspond  to  the  southwest  of  the  northern.  Continuing  on  to 
the  southeast,  they  are  now  the  surface  winds ;  they  are  going 
from  warmer  to  cooler  latitudes ;  they  become  as  the  wet 
sponge,  and  are  abruptly  intercepted  by  the  Andes  of  Pata- 
gonia, whose  cold  summit  compresses  them,  and  with  its  low 
dew-point  squeezes  the  water  out  of  them.  Captain  King  found 
the  astonishing  fall  of  water  here  of  nearly  thirteen  feet  (one 
hundred  and  fifty-one  inches)  in  forty-one  days ;  and  Mr.  Dar- 
win reports  that  the  sea-water  along  this  part  of  the  South 
American  coast  is  sometimes  quite  fresh,  from  the  vast  quan- 
tity of  rain  that  falls.  A  similar  rainfall  occurs  on  the  sides 
of  Cherraponjie,  a  mountain  in  India.  Colonel  Sykes  reports 
a  fall  here  during  the  southwest  monsoons  of  six  hundred  and 
five  and  one-quarter  inches.  This  is  at  the  rate  of  eighty -six 
feet  during  the  year ;  but  King's  Patagonia  rainfall  is  at  the 
rate  of  one  hundred  and  fourteen  feet  during  the  year.  Cher- 
raponjie is  not  so  near  the  coast  as  the  Patagonia  range,  and 
the  monsoons  lose  moisture  before  they  reach  it." 


DRAINAGE.  109 


XI.  DRAINAGE. 

THE  rain  that  falls  on  the  earth  either  runs 
directly  off  the  surface  or  sinks  into  the  ground. 

The  part  that  runs  directly  off  the  surface  col- 
lects in  small  streams  that  discharge  through  a 
river,  either  into  a  lake  or  into  the  ocean. 

The  part  which  sinks  into  the  ground  collects  in 
pockets  or  places  below  the  surface,  called  reser- 
voirs. As  a  rule,  the  water  escapes  from  these 
underground  reservoirs  by  coming  out  at  the  sur- 
face at  some  lower  level,  as  a  spring.  During  most 
of  the  time  the  now  of  water  in  a  river  is  kept 
up  by  the  springs  pouring  their  waters  into  the 
many  streams  that  empty  into  the  river  channel. 

The  water,  therefore,  that  falls  from  the  sky  as 
rain,  flows  directly  from  the  earth's  surface  into  a 
river,  or  first  collects  in  a  reservoir,  from  which  it 
afterwards  flows  into  a  river. 

The  running  of  the  water  from  the  level  where 
the  rain  fell  to  a  lower  level  is  called  drainage. 

There  are  two  kinds  of  drainage : 
10 


110  OUTLINES  OF  FORESTRY. 

1.  Surface  drainage,  or  where    the    rain-water 
runs  directly  off  the  surface. 

2.  Underground  drainage,   or  where  the   rain- 
water first  sinks  into  the  ground  and  then  dis- 
charges as  springs  into  some  stream  that  empties 
into  a  river. 

Surface  drainage,  for  the  greater  part,  takes 
place  rapidly,  and  occurs  mainly  during  the  time 
rain  is  falling.  It  practically  stops  a  few  hours 
after  the  rain  ceases. 

Underground  drainage  takes  place  slowly,  and 
may  continue  for  many  weeks  after  the  rain  ceases. 

All  the  water  in  a  river  comes  from  the  rain  that 
falls  on  the  earth's  surface.  The  rivers  continue 
to  flow  because  the  springs  are  continually  empty- 
ing their  waters  into  the  rivers,  and,  before  they 
run  dry,  more  rain  falls  and  keeps  up  the  supply 
in  their  reservoirs. 

Some  rivers  are  larger  than  others.  This  is 
because : 

1.  More  rain  falls  on  those  parts  of  the  earth 
through  which  they  flow. 

2.  The  land  which  slopes  towards  such  rivers 
covers  a  greater  part  of  the  earth's  surface. 

The  water  runs  off  the  earth  from  a  higher  to  a 
lower  level,  because  water  runs  down  hill.  The 


DRAINAGE.  Ill 

t 

direction  in  which  water  will  drain  from  the  land 
will  depend  on  the  direction  of  the  slope  of  the 
land.  If  a  large  area  of  land  so  slopes  that  all  the 
water  draining  from  it  collects  in  streams  flowing 
into  the  ocean  through  a  common  river  mouth, 
and  the  rainfall  on  such  area  is  large,  the  river 
itself  will  be  large. 

The  smaller  streams  and  rivers  which  collect  in  a 
single  and  larger  river,  and  discharge  their  waters 
through  a  common  mouth,  are  called,  collectively, 
a  river  system. 

The  area  of  land  that  drains  into  a  river  is  called 
a  river  basin. 

The  size  of  a  river,  therefore,  depends  upon  the 
amount  of  the  rainfall  on  its  basin,  and  on  the  size 
of  its  basin. 

When  the  quantity  of  water  discharged  into  a 
river  is  greater  than  its  channel  can  hold,  a  flood 
occurs,  or  the  river  is  said  to  inundate  its  banks. 

A  heavy  rain-fall  does  not  necessarily  produce 
an  inundation.  If  the  character  of  the  river  basin 
is  such  that  a  comparatively  small  part  of  the  rain- 
fall runs  directly  off  the  surface,  and  a  large  part 
sinks  into  the  ground  and  collects  in  the  reservoirs 
of  springs,  and  slowly  passes  through  such  springs 
into  the  rivers,  sufficient  time  may  be  given  for 


11.2  OUTLINES  OF  FORESTRY. 

the  river  to  safely  discharge  the  waters  of  even  a 
very  heavy  rainfall. 

If,  however,  the  character  of  the  surface  is  such 
that  the  larger  part  of  the  rainfall  runs  directly  off 
the  slopes  into  the  river  channel,  then  an  inunda- 
tion must  necessarily  attend  every  heavy  rainfall. 

If  the  greater  part  of  the  rainfall  runs  directly 
off  the  surface  into  the  river  channel,  and  a  com- 
paratively small  part  goes  to  feed  the  reservoirs  of 
the  springs,  and  if  a  long  time  elapses  hefore  the 
next  rainfall,  the  springs  will  dry  up,  and  the 
water  in  the  river  will  get  very  low. 

Any  disturbance  in  the  natural  drainage  of  a 
country  may  cause  a  damage  of  two  different 
kinds: 

1.  The  damage  due  to  the  overflowing  of  the 
rivers,  or  that  directly  due  to  too  much  water. 

2.  The  damage   due  to  the  drying  up,  or  the 
getting  too  low,  of  the  rivers  in  the  intervals  be- 
tween the  storms,  or  that  due  to  too  little  water. 

The  proportion  of  the  rainfall  that  sinks  quietly 
into  the  earth,  as  compared  with  that  which  flows 
directly  off  its  surface,  depends  on  the  character 
of  the  surface.  As  a  rule,  a  surface  devoid  of 
vegetable  covering — that  is,  a  surface  on  which 
no  vegetation  is  growing — will  permit  a  larger 


DRAINAGE.  113 

proportion  of  the  rainfall  to  drain  directly  into  the 
river  channels  than  will  a  surface  covered  by 
vegetation.  This  is  especially  the  case  during  the 
colder  parts  of  the  year,  when  the  ground  is  frozen. 

"When  rain  falls  on  a  surface  covered  by  vegeta- 
tion, the  water,  by  slowly  trickling  down  the  stalks 
or  stems  of  the  leaves  and  the  branches  and  trunks 
of  the  trees,  finds  a  ready  entrance  into  the  ground 
by  following  their  surfaces  and  discharging  into 
the  porous  ground  lying  around  their  roots. 

A  forest  permits  this  action  of  the  water  in  sink- 
ing into  the  ground  to  take  place  quite  readily. 

A  forest,  therefore,  tends  to  decrease  the  amount 
of  rainfall  that  drains  directly  from  the  earth's 
surface. 

A  forest  also  tends  to  prevent  the  occurrence  of 
too  little  water  in  a  river,  because  it  insures  the 
filling  of  the  reservoirs  of  springs,  which  discharge 
their  waters  into  the  rivers  during  the  intervals 
between  the  rainfalls. 

Unless,  therefore,  forests  are  preserved,  the 
proper  drainage  of  the  earth  will  be  disturbed, 
and  the  rivers  will  have  too  much  water  in  their 
channels  during  the  time  of  rains,  and  too  little 
water  in  the  intervals  between  rains. 

The  rapid  drainage  of  the  surface  when  no 
h  10* 


114  OUTLINES  OF  FORESTRY. 

longer  protected  by  the  forests  is  thus  described 
by  Sir  Charles  Lyell,  in  his  "  Principles  of  Ge- 
ology, or  the  Modern  Changes  of  the  Earth  and 
its  Inhabitants,"  *  on  page  338,  vol.  i. : 

"  When  travelling  in  Georgia  and  Alabama  in  1846,  I  saw 
in  both  these  States  the  commencement  of  hundreds  of  val- 
leys in  places  where  the  native  forests  had  recently  been  re* 
moved.  One  of  these  newly-formed  gulleys  or  ravines  is 
represented  in  the  annexed  wood-cut,  from  a  drawing  which 
I  made  on  the  spot.  It  occurs  three  miles  and  a  half  due  west 
of  Milledgeville,  the  capital  of  Georgia,  and  is  situated  on  the 
farm  of  Pomona,  on  the  direct  road  to  Macon. 

"  In  1826,  before  the  land  was  cleared,  it  had  no  existence ; 
when  the  trees  of  the  forest  were  cut  down,  cracks  three  feet 
deep  were  caused  by  the  sun's  heat  in  the  clay ;  and  during 
the  rains,  a  sudden  rush  of  water  through  the  principal  crack 
deepened  it  at  its  lower  extremity,  from  whence  the  excavating 
power  worked  backward,  till,  in  the  course  of  twenty  years,  a 
chasm  measuring  no  less  than  fifty-five  feet  in  depth,  three 
hundred  yards  in  length,  and  varying  in  width  from  twenty  to 
one  hundred  and  eighty  feet,  was  the  result.  The  high  road 
had  been  several  times  turned  to  avoid  this  cavity,  the  enlarge- 
ment of  which  is  still  proceeding,  and  the  old  line  of  road  may 
be  seen  to  have  held  its  course  directly  over  what  is  now  the 
widest  part  of  the  ravine.  In  the  perpendicular  walls  of  this 

*"  Principles  of  Geology,"  by  Sir  Charles  Lyell,  F.R.S., 
M.A.  London:  John  Murray,  Albemarle  Street,  1872.  Pp. 
650. 


DRAINAGE.  115 

great  chasm  appear  beds  of  clay  and  sand,  red,  white,  yellow, 
and  green,  produced  by  the  decomposition  in  situ  of  hornbl  en- 
die  gneiss  with  layers  and  veins  of  quartz,  which  remains  en- 
tire to  prove  that  the  whole  mass  was  once  crystalline." 

Marsh,  in  his  book  on  "  The  Earth  as  Modified 
by  Human  Action,"  *  in  referring  to  the  effects 
produced  on  the  drainage  of  the  land  by  the  de- 
struction of  the  forest,  on  page  254,  gives  the  fol- 
lowing quotation  from  a  paper  read  by  Blanqui, 
read  before  the  Academy  of  Moral  and  Political 
Science  in  1843,  concerning  the  Alps  of  Provence  : 

"  The  Alps  of  Provence  present  a  terrible  aspect.  In  the 
more  equable  climate  of  Northern  France,  one  can  form  no 
conception  of  those  parched  mountain  gorges  where  not  even 
a  bush  can  be  found  to  shelter  a  bird,  where,  at  most,  the  wan- 
derer sees  in  summer  here  and  there  a  withered  lavender, 
where  all  the  springs  are  dried  up,  and  where  a  dead  silence, 
hardly  broken  by  even  the  hum  of  an  insect,  prevails.  But  if 
a  storm  bursts  forth,  masses  of  water  suddenly  shoot  from  the 
mountain  heights  into  the  shattered  gulfs,  waste  without  irri- 
gating, deluge  without  refreshing  the  soil  they  overflow  in 
their  swift  descent,  and  leave  it  even  more  seared  than  it  was 
from  want  of  moisture.  Man  at  last  retires  from  the  fearful 

*  Eeprinted,  by  permission,  from  "  The  Earth  as  Modified 
by  Human  Action,"  by  George  P.  Marsh.  New  York  :  Scrib- 
ner,  Armstrong  &  Co.,  No.  654  Broadway,  1874.  Pp.  656. 


116  OUTLINES  OF  FORESTRY. 

desert,  and  I  have,  the  present  season,  found  not  a  living  soul 
in  districts  where  I  remember  to  have  enjoyed  hospitality 
thirty  years  ago." 

The  influence  of  a  vegetable  covering  on  the 
drainage  of  the  surface  is  thus  referred  to  by  fili- 
see  Reclus,  in  his  work  on  "  The  Earth :  A  De- 
scriptive History  of  the  Phenomena  of  the  Life  of 
the  Globe,"  *  on  page  223  : 

"  The  action  of  vegetation  is  not  confined  merely  to  imbibing 
the  water  falling  from  the  clouds ;  it  often,  also,  assists  the 
superabundant  moisture  in  penetrating  the  interior  of  the 
ground.  Trees,  after  they  have  received  the  water  upon  their 
foliage,  let  it  trickle  down  drop  by  drop  on  the  gradually 
softened  earth,  and  thus  facilitate  the  gentle  permeation  of 
the  moisture  into  the  substratum ;  another  part  of  the  rain- 
water, running  down  the  trunk  and  along  the  roots,  at  once 
finds  its  way  to  the  lower  strata.  On  mountain  slopes,  the  mosses 
and  the  freshly-growing  carpet  of  Alpine  plants  swell  like 
sponges  when  they  are  watered  with  rain  or  melted  snow,  and 
retain  the  moisture  in  the  interstices  of  their  leaves  and  stalks 
until  the  vegetable  mass  is  thoroughly  saturated  and  the  liquid 
surplus  flows  away.  Peat-mosses  especially  absorb  a  very  con- 
siderable quantity  of  water,  and  form  great  feeding-reservoirs 
for  the  springs  which  gush  out  at  a  lower  level.  The  immense 

*  Eeprinted,  by  permission,  from  "  The  Earth,"  by  Elise*e 
Keclus.  New  York:  Harper  &  Brothers,  Franklin  Square. 
Pp.  573. 


DRAINAGE.  117 

fields  of  peat  which  cover  hundreds  and  thousands  of  acres  on 
the  mountain  slopes  of  Ireland  and  Scotland  may,  notwith- 
standing their  elevation  and  inclined  position,  be  considered 
as  actual  lacustrine  basins  containing  millions  of  tons  of  water 
dispersed  among  their  innumerable  leaflets.  The  supera- 
bundant water  of  these  tracks  of  peat-mosses  issues  forth  in 
springs  on  the  plains  below." 

The  protective  action  of  a  vegetable  covering  is 
thus  alluded  to  by  Prestwich  in  his  "  Geology, 
Chemical,  Physical,  and  Stratigraphical,"  *  page 
136: 

"  This  surface  soil,  with  its  usual  covering  of  herbage,  serves 
to  protect  the  land  from  further  degradation,  and  checks  the 
denuding  action  which  would  otherwise  scour  the  surface  after 
every  shower  of  rain.  Instances  have  been  adduced  to  show 
how  persistent  are  the  features  of  such  a  surface.  The  posi- 
tions of  the  many  dolmens  and  other  so-called  '  DruidicaP 
stones,  so  common  on  the  downs  of  this  country  and  in  many 
parts  of  France,  shows  that  the  level  of  the  vegetable  soil  has 
undergone  little  or  no  change  since  they  were  first  erected. 
The  camp  of  Attila,  situated  in  the  great  chalk  plains  of 
Champagne,  furnishes  a  well-known  date,  namely,  A.D.  451. 
Notwithstanding  its  more  than  fourteen  hundred  years,  the 

*  Keprinted,  by  permission,  from  "  Geology,  Chemical,  Physi- 
cal, and  Stratigraphical,"  by  Joseph  Prestwich,  M.A.,  F.R.S. 
Vol.  i.  Oxford,  Clarendon  Press,  1886.  Pp.  477. 


118  OUTLINES  OF  FORESTRY. 

surface  of  this  great  earthwork,  which  is  merely  covered  with 
a  thin  growth  of  grass,  remains  almost  as  perfect  and  as  sharp 
as  when  first  made  and  grassed  over.  Nothing  of  importance 
has  been  removed  from  the  surface  by  mechanical  means,  what- 
ever may  have  been  the  solvent  action  of  the  rain  on  the  rocks 
beneath." 


CLIMATE.  119 


XII.  CLIMATE. 

BY  the  climate  of  a  country  is  meant  the  condi- 
tion of  its  atmosphere  as  regards  heat  or  cold, 
moisture  or  dryness,  healthfulness  or  unhealthful- 
ness. 

The  atmosphere,  or  ocean  of  air  that  surrounds 
the  earth,  gets  practically  all  its  heat  from  the 
sun,  either  directly  hy  absorption  as  the  rays  pass 
through  the  air,  or  indirectly  from  the  heated 
earth. 

Or,  less  concisely,  the  atmosphere  receives  its 
heat  from  the  sun : 

1.  Directly,  by  absorption. 

2.  Indirectly,  from  the  heated  earth. 
(a.)  By  contact  with  the  heated  earth. 

(6.)  By  radiation  from  the  heated  earth, — that  is, 
the  sun's  rays  heat  the  earth,  and  the  heated  earth 
throws  out  or  radiates  its  heat  in  all  directions. 

(c.)  By  reflection  from  the  heated  earth, — that  is, 
the  sun's  rays  strike  the  earth  and  fly  off  from  it 
like  light  does  when  it  strikes  a  mirror. 

The  equatorial  regions  of  the  earth  are  warmer 


120  OUTLINES  OF  FORESTRY. 

than  either  the  temperate  or  the  polar  regions, 
because  they  receive  the  sun's  rays  more  directly 
than  any  other  part  of  the  earth. 

Regions  of  the  earth  that  are  situated  the  same 
distance  from  the  equator,  however,  often  possess 
different  temperatures,  not  only  because  they  are 
exposed  to  warmer  or  colder  currents  of  air  or 
water,  but  also  on  account  of  certain  peculiarities 
of  their  surfaces 

The  distribution  of  the  land  and  water  areas  of 
the  earth  exerts  a  marked  influence  in  causing  a 
difference  in  climate  in  regions  situated  in  the 
same  latitude. 

A  given  quantity  of  the  sun's  heat  falling  on  a 
given  area  of  water  will  produce  therein  a  smaller 
increase  of  temperature  than  if  permitted  to  fall 
on  an  equal  area  of  land.  Consequently,  the  air 
over  such  body  of  water  will  be  less  warmed  than 
would  the  air  over  the  land. 

"Water  possesses  a  greater  capacity  for  heat  than 
any  other  common  substance;  in  other  words,  a 
greater  quantity  of  heat  is  required  to  cause  a  cer- 
tain increase  of  temperature  in  a  pound  of  water 
than  in  a  pound  of  any  other  common  substance. 

For  example :  the  quantity  of  heat  required  to 
raise  a  pound  of  ice-cold  water  to  its  boiling-point, 


CLIMATE.  121 

or  to  212  degrees  Fahrenheit,  would  be  sufficient 
to  raise  the  temperature  of  a  pound  of  ice-cold 
iron  to  about  1600  degrees  Fahrenheit,  or  to  make 
the  ice-cold  iron  red-hot. 

Although  land  and  water  areas  may  be  situated 
in  the  same  latitude,  and  therefore  receive  equal 
quantities  of  the  sun's  heat  per  unit  of  area,  yet 
the  temperature  of  the  land,  and  consequently  of 
the  air  over  it,  would  become  much  hotter  than 
the  temperature  of  the  water,  and  of  the  air  over 
the  water. 

The  higher  the  temperature  of  an  area,  the  more 
rapidly  it  loses  its  heat.  A  land  surface,  when 
heating,  becomes  hotter  than  a  water  surface  when 
similarly  exposed  for  the  same  time  to  the  sun's 
heat.  The  land  also,  when  cooling,  loses  its  heat 
more  rapidly  than  the  water ;  the  air  over  the  land 
becomes  chilled  sooner  than  over  the  water. 

Differences  in  the  elevation  of  the  land  produce 
differences  in  the  climate.  In  general,  an  elevation 
of  three  hundred  and  fifty  feet  will  cause  as  great 
a  lowering  of  temperature  as  a  difference  of  one 
degree  of  latitude,  or  of  about  seventy  geograph- 
ical miles.  Therefore,  the  same  differences  are 
observed  in  passing  from  the  base  to  the  summit 
of  a  high  tropical  mountain  as  are  observed  in 

F  11 


122  OUTLINES  OF  FORESTRY. 

passing  along  the  surface  of  the  earth  from  the 
equator  to  the  poles.  Or,  in  other  words,  three 
hundred  and  fifty  feet  skyward  equals  seventy 
miles  poleward. 

In  summer,  when  the  sun  is  more  nearly  over- 
head, and  when  in  our  hemisphere  the  earth  is 
gaining  rather  than  losing  heat,  the  land  areas, 
and  consequently  the  air  over  them,  rapidly  become 
heated;  while  the  water  areas,  and  consequently 
the  air  over  them,  remain  comparatively  cool. 

In  winter,  however,  when  the  loss  of  heat  is 
greater  than  the  gain,  the  land  areas,  and  conse- 
quently the  air  over  them,  rapidly  become  cooled; 
while  the  water  areas  continue  for  a  long  time  to 
part  with  the  great  stores  of  heat  that  they  have 
taken  in  during  the  summer,  and  thus  remain 
comparatively  warm. 

Similar  differences  are  observed  between  the 
temperature  of  the  air  over  the  land  and  water 
areas  during  the  daylight  while  they  are  exposed 
to  the  sun's  heat,  and  during  the  night  when  they 
are  throwing  it  off. 

There  is  another  reason  why  the  water  areas  are 
heated  less  rapidly  than  the  land  areas :  the  heat 
penetrates  the  water  to  a  comparatively  great 
depth,  is  diffused  through  a  great  body  of  water, 


CLIMATE.  123 

and,  consequently,  heats  it  less.  Moreover,  the 
water  when  heated  is  set  in  motion  by  reason  of 
the  differences  of  density  produced  by  the  differ- 
ences of  temperature,  and  moves  towards  colder 
districts,  and  its  place  is  taken  by  water  that  moves 
from  colder  districts.  Such  motions  are  seen  in 
the  constant  ocean  currents. 

The  land,  on  the  contrary,  is  heated  to  a  com- 
paratively small  depth,  remains  in  its  place,  and 
may,  therefore,  rapidly  become  intensely  hot. 

The  climate  produced  by  an  extended  land  area 
is  called  a  continental  climate.  That  produced  by 
an  extended  water  area  is  called  an  oceanic  climate. 
The  continental  climate  is  characterized  by  great 
extremes  of  heat  and  cold, — that  is,  a  continental 
climate  is  apt  to  be  very  hot  in  summer  and  very 
cold  in  winter.  The  oceanic  climate,  on  the  con- 
trary, is  characterized  by  a  comparatively  uniform 
temperature,  being  neither  very  hot  in  summer  nor 
very  cold  in  winter. 

So  far  as  the  climate  of  the  land  is  concerned, 
the  differences  of  climate  above  referred  to  are 
greatly  influenced  by  the  nature  of  the  surface. 
If  the  surface  is  covered  by  vegetation  of  any  kind, 
especially  by  forests,  it  both  heats  slowly  and  cools 
slowly. 


124  OUTLINES  OF  FORESTRY. 

If  entirely  bare,  or  deprived  of  vegetable  cover- 
ing, it  both  heats  quickly  and  cools  quickly. 

The  climate  of  a  forest,  or,  indeed,  even  of  a  re- 
gion protected  by  a  less  dense  covering  of  vegeta- 
tion, closely  resembles  the  equable  climate  of  a 
water  area;  that  of  a  bare,  arid  district,  differs 
greatly  from  that  of  a  water  area.  Deserts,  for 
example,  are  characterized  by  great  extremes  of 
climate,  being  very  warm  in  summer,  or  in  the 
daytime,  and  very  cold  in  winter,  or  at  night. 

The  climate  of  a  country,  therefore,  will  be 
greatly  influenced  by  the  presence  of  the  forest 
districts,  and  must  necessarily  be  changed,  to  a 
greater  or  less  extent,  by  the  removal  of  such 
forests  from  extended  areas. 

Humboldt,  in  "  Cosmos,"  *  on  page  318,  thus 
describes  the  influence  of  land  and  water  areas  on 
oceanic  or  continental  climates ;  or,  as  he  styles 
them,  on  the  insular  or  littoral  climates : 

"I  have  already  alluded  to  the  slowness  with  which  the 
great  mass  of  water  in  the  ocean  follows  the  variations  of 
temperature  in  the  atmosphere,  and  the  consequent  influence 
of  the  sea  in  equalizing  temperatures ;  it  moderates  both  the 

*  "  Cosmos,"  vol.  i.,  by  Alexander  von  Humboldt.  London : 
Longman,  Brown,  Green  &  Longmans,  1849.  Pp.  480. 


CLIMATE.  125 

asperity  of  winter  and  the  heat  of  summer :  hence  arises  a 
second  important  contrast, — that  between  insular  or  littoral 
climates  (enjoyed  also  in  some  degree  by  continents  whose 
outline  is  broken  by  peninsulas  and  bays),  and  the  climate  of 
the  interior  of  great  masses  of  solid  land.  Leopold  von  Buch 
was  the  first  writer  who  entered  fully  into  the  subject  of  this 
remarkable  contrast,  and  the  varied  phenomena  resulting  from 
it ;  its  influence  on  agriculture  and  vegetation,  on  the  transpar- 
ency of  the  atmosphere  and  the  serenity  of  the  sky,  on  the 
radiation  from  the  surface,  and  on  the  height  and  limit  of  per- 
petual snow.  In  the  interior  of  the  Asiatic  continent,  Tobolsk, 
Barnaul  on  the  Obi,  and  Irkutsk  have  summers  which,  in 
mean  temperature,  resemble  those  of  Berlin  and  Munster,  and 
that  of  Cherbourg  in  Normandy,  and  during  this  season  the 
thermometer  sometimes  remains  for  weeks  together  at  30°  and 
31°  C.  (86°  or  87.8°  F.) ;  but  these  summers  are  followed  by 
winters  in  which  the  coldest  month  has  the  severe  mean  tem- 
perature of  18°  to  20°  C.  (—4°  to  +4°  F.)." 

Flammarion,  in  his  work  entitled  "  The  Atmos- 
phere," *  referring  to  the  contrasts  between  con- 
tinental and  oceanic  climates,  says,  on  page  250  : 

"  The  climate  of  Ireland,  Jersey  and  Guernsey,  of  the  Pen- 
insula of  Brittany,  of  the  coasts  of  Normandy,  and  the  South 
of  England,  countries  in  which  the  winters  are  mild  and  the 

*  Eeprinted,  by  permission,  from  "  The  Atmosphere,"  by 
Camille  Flammarion.  New  York :  Harper  &  Brothers,  Frank- 
lin Square,  1873.  Pp.  454. 

11* 


126  OUTLINES  OF  FORESTRY. 

summers  cool,  contrast  very  strikingly  with  the  continental 
climate  of  the  interior  or  Eastern  Europe.  In  the  northeast 
of  Ireland  (54°  56X),  in  the  same  latitude  as  Konigsberg,  the 
myrtle  grows  in  the  open  ground  just  as  it  does  in  Portugal. 
The  temperature  of  the  month  of  August  in  Hungary  is  69.8°  ; 
in  Dublin  (upon  the  same  isothermal  line  of  49°)  it  is  61°  at 
most.  The  mean  temperature  of  winter  descends  to  36.3°  at 
Buda.  In  Dublin,  where  the  annual  temperature  is  only  49°, 
that  of  the  winter  is,  nevertheless,  7.7°  above  the  freezing- 
point,  or  nearly  four  degrees  higher  than  at  Milan,  Pavia, 
Padua,  and  all  Lombardy,  where  the  mean  heat  of  the  year 
reaches  55°.  In  the  Orkney  Islands,  at  Stromness,  a  little  to 
the  south  of  Stockholm  (there  is  not  one  degree  difference  in 
their  latitudes),  the  mean  winter  temperature  is  7°,  or  higher 
than  that  of  London  or  Paris.  Stranger  still,  the  inland 
waters  of  the  Faroe  Islands  never  freeze,  situated  in  62°  of 
north  latitude,  beneath  the  mild  influences  of  the  west  wind 
and  the  sea.  Upon  the  coast  of  Devonshire,  one  part  of 
which  has  been  termed  the  Montpellier  of  the  North,  because 
of  the  mildness  of  its  climate,  the  Agave  Mexicana  has  been 
known  to  flower  when  planted  in  the  open  air,  and  orange- 
trees  trained  upon  the  wall  to  bear  fruit,  though  only  scantily 
protected  by  a  thin  matting. 

"  There,  as  at  Penzance,  Gosport,  Cherbourg,  and  the  coast 
of  Normandy,  the  mean  temperature  of  the  winter  is  42°, 
being  but  18.5°  below  that  of  Montpellier  and  Florence." 


CLIMATE  AS  INFLUENCED  BY  THE  FOREST.      127 


XIII.    CLIMATE     AS     INFLUENCED     BY 
THE   PRESENCE   OF   THE    FOREST. 

"WHEN  sunshine  falls  on  an  area  covered  by  trees, 
the  heat  is  more  thoroughly  absorbed  or  taken  in 
than  when  it  falls  on  an  arid  or  uncovered  surface. 

The  more  thorough  absorption  of  heat  by  a 
wooded  area  is  caused  mainly  as  follows : 

1.  The  greater  extent  of  surface  presented  by  a 
wooded  than  by  an  unwooded  area,  not  only  by 
the  trees  themselves,  but  often  also  by  the  under- 
brush which  exists  in  most  forest  regions. 

2.  The  porous  and  better  absorbing  character 
of  the  carpet  of  leaves  that  generally  covers  the 
ground  in  forest  regions. 

3.  The  presence  of  a  greater  amount  of  moisture 
in  the  air  of  a  forest  region  than  in  a  region  that 
is  void  of  vegetation. 

The  marked  increase  in  the  area  of  a  surface 
covered  by  a  forest  over  that  of  an  equally  large 
unwooded  surface  would  itself,  apart  from  any 
other  circumstances,  necessitate  a  smaller  rise  or  in- 
crease of  temperature  in  the  forest  than  would  the 


128  OUTLINES  OF  FORESTRY. 

same  quantity  of  the  sun's  heat  falling  on  an  equal 
area  of  bare  ground.  Therefore,  the  sun's  heat 
when  permitted  to  fall  on  a  forest  region  is  more 
thoroughly  absorbed,  is  spread  over  a  greater  sur- 
face, and  penetrates  the  ground  more  thoroughly 
than  it  would  if  thrown  on  bare  ground.  For, 
when  the  rays  fall  on  a  bare,  dry,  parched  surface, 
they  penetrate  the  ground  to  but  a  small  depth, 
and  heating  a  smaller  amount,  must  necessarily 
produce  a  greater  increase  of  temperature. 

The  same  is  true  as  regards  the  loss  of  heat: 
forest  districts,  which  take  in  heat  slowly,  part 
with  it  slowly;  while  bare,  uncovered  surfaces, 
which  take  in  heat  quickly,  part  with  it  quickly. 

It,  therefore,  follows  that  since  the  forests  do  not 
rapidly  heat,  they  do  not  become  excessively  hot 
in  summer;  and,  since  they  part  with  their  heat 
slowly,  they  do  not  become  very  cold  in  winter. 

The  fact  that  an  area  covered  with  forests  does 
not  tend  to  become  as  cold  in  winter  as  bare, 
uncovered  ground,  exerts  a  great  influence  on  the 
depth  to  which  the  frost  extends  downwards. 

The  non-conducting  power  for  heat  of  even  a 
very  thin  layer  of  snow  is  well  known.  If  snow 
falls  before  the  frost  penetrates  the  ground  to  any 
great  depth,  it  will  act  as  a  covering  to  prevent  the 


CLIMATE  AS  INFLUENCED  BY  THE  FOREST.      129 

earth  from  losing  heat.  The  frost  will,  therefore, 
he  prevented  from  entering  the  ground  to  any  great 
depth.  In  the  temperate  regions  of  the  Northern 
Hemisphere,  in  districts  covered  by  forests,  the 
early  snows  of  winter  are,  for  the  greater  part,  apt 
to  fall  before  the  ground  is  frozen  to  any  con- 
siderable depth.  In  the  early  spring,  when  the 
thaws  come,  the  water  derived  from  the  melting 
of  the  ice  and  snow  can  then  drain  quietly  into  the 
ground  and  fill  the  reservoirs  of  the  springs. 

If,  however,  the  forests  are  removed,  the  ease 
with  which  the  ground  loses  its  heat  generally  per- 
mits it  to  freeze  before  the  first  snow  falls,  and  the 
non-conducting  power  of  the  layer  of  snow  causes 
the  ground  to  remain  frozen  until  long  after  the 
spring  thaws  have  melted  the  snow.  Under  such 
circumstances,  the  water  derived  from  the  melting 
snow  rapidly  drains  almost  entirely  off  the  sur- 
face, and  is  apt  to  produce  disastrous  floods. 

Tyndall  has  shown  that  the  ability  of  air  to  be- 
come heated,  by  absorbing  heat  directly  from  the 
sun's  rays  as  they  pass  through  it,  depends  almost 
entirely  on  the  presence  of  water  vapor.  The  air 
over  a  forest  district  is  necessarily  more  moist,  and 
consequently  better  able  to  absorb  heat  and  become 
heated  than  the  air  over  a  dry,  barren  tract. 
i 


130  OUTLINES  OF  FORESTRY. 

Moist  air,  moreover,  is  not  only  better  able  to 
absorb  the  heat  accompanying  the  direct  rays  of 
the  sun,  but  is  especially  able  to  absorb  that  kind 
of  heat  which  is  thrown  off  from  the  heated  earth. 
Consequently,  the  air  over  a  forest  district  absorbs 
a  much  larger  percentage  of  the  heat  flung  off 
from  the  heated  earth  than  does  the  drier  air  over 
a  barren  district.  In  this  way,  in  winter,  while  the 
ground  is  throwing  off  its  heat,  the  moist  air  of 
the  forest  tends  to  remain  warmer  than  the  air 
over  a  dry,  arid  tract. 

Forests  exert  a  marked  influence  on  the  climate 
of  a  country,  especially  at  that  time  of  the  year 
when  the  crops  are  liable  to  suffer  injury  from 
early  frosts. 

The  ease  with  which  bare  or  poorly  covered 
ground  throws  off  its  heat  permits  such  an  area  to 
more  readily  reach  the  temperature  of  the  danger- 
point  than  would  be  the  case  if  it  were  well 
wooded.  It  must  be  remembered  that  the  differ- 
ence of  a  few  degrees,  or  even  of  the  fraction  of  a 
degree,  between  the  air  over  an  uncovered  district, 
and  the  air  over  a  covered  district  in  the  forest, 
may  make  all  the  difference  between  the  occurrence 
of  frost  and  its  non-occurrence.  It  is,  indeed,  often 
but  the  difference  of  a  fraction  of  a  degree,  that 


CLIMATE  AS  INFLUENCED  BY  THE  FOREST.      131 

may  cause  by  an  early  frost  the  loss  of  millions  of 
dollars  to  an  agricultural  district. 

Again,  it  is  in  the  late  autumn,  at  the  time  of  the 
early  frosts  which  are  so  feared  in  the  agricultural 
districts,  that  a  vegetable  covering  may  be  able  to 
fling  back  to  the  earth  sufficient  heat  thrown  out 
by  the  cooling  ground  to  prevent  the  temperature 
of  the  air  immediately  around  growing  plants 
from  reaching  the  freezing-point. 

Forests  exert  a  sheltering  action  at  the  time  of 
frosts  in  keeping  the  land  to  the  leeward  warmer 
than  that  to  the  windward.  Not  only  do  they 
act  as  an  actual  barrier  or  screen,  sheltering  and 
protecting  the  land  immediately  to  the  leeward 
side,  but  this  protecting  action  extends  to  a  much 
greater  distance  beyond  the  immediate  neighbor- 
hood of  the  forest  than  might  be  supposed. 

The  leaves  of  almost  any  forest  tree,  when  ex- 
amined under  the  microscope,  show  greatly  ex- 
tended surfaces  in  the  shape  of  irregularities,  or 
spine-like  projections.  These  extended  surfaces 
aid  the  tree  greatly  in  throwing  off  from  the  very 
slightly  heated  earth  the  stores  of  heat  which  it 
possesses,  even  in  the  depth  of  winter,  and  which, 
thus  passing  into  the  air,  tend  to  prevent  a  too 
marked  fall  of  temperature  during  winter. 


132  OUTLINES  OF  FORESTRY. 

Generally,  the  air  of  the  forest  is  cooler  and 
damper  in  summer  than  the  air  over  the  open 
fields  in  the  same  district. 

1st.  Because  the  air  of  the  forest  is  shielded 
from  the  direct  rays  of  the  sun. 

2d.  Because  the  air  is  chilled  by  evaporation  from 
the  moister  ground. 

A  large  tract  of  forest  in  any  section  of  country 
tends  to  prevent  marked  changes  in  its  climate,  as 
compared  with  those  that  occur  in  the  same  region 
over  the  open  fields. 

1.  By  permitting  the  wooded  area  to  more  thor- 
oughly absorb  the  sun's  heat  on  account  of  the 
greater  surface  it  presents. 

2.  By  keeping  the  air  moister  and,  therefore, 
better  able  to  absorb  the  sun's  heat. 

3.  By  acting  as  a  screen  to  the  land  to  the  lee- 
ward of  a  cold  wind. 

4.  By  preventing  the  frost  from  penetrating  the 
ground  to  too  great  a  depth  before  protected  by  a 
covering  of  snow. 

Geikie,  in    his   "  Text-Book  of  Geology,"  *  in 


*  Reprinted,  by  permission,  from  "  Text-Book  of  Geology," 
by  Archibald  Geikie,  LL.D.,  F.R.S.  London :  Macmillan  & 
Co.,  1882.  Pp.971. 


CLIMATE  AS  INFLUENCED  BY  THE  FOREST.      133 

referring  to  the  manner  in  which  man  may  influ- 
ence the  climate  of  any  particular  part  of  the 
earth,  says  on  page  471 : 

"  Human  interference  affects  meteorological  conditions :  1, 
by  removing  forests  and  laying  bare  to  the  sun  and  winds 
areas  which  were  previously  kept  cool  and  damp  under  trees, 
or  which,  lying  on  the  lee  side,  were  protected  from  tempests  ; 
as  already  stated,  it  is  supposed  that  the  wholesale  destruction 
of  the  woodlands  formerly  existing  in  countries  bordering  the 
Mediterranean  has  been  in  part  the  cause  of  the  present  desic- 
cation of  these  districts;  2,  by  drainage,  the  effect  of  this 
operation  being  to  remove  rapidly  the  discharged  rainfall,  to 
raise  the  temperature  of  the  soil,  to  lessen  the  evaporation,  and 
thereby  to  diminish  the  rainfall  and  somewhat  increase  the 
general  temperature  of  a  country ;  3,  by  the  other  processes 
of  agriculture,  such  as  the  transformation  of  moor  and  bog 
into  cultivated  land,  and  the  clothing  of  bare  hill-sides  with 
green  crops  or  plantations  of  coniferous  and  hard-wood  trees." 

Not  only  does  the  forest  prevent  the  excessive 
heating  of  the  land  on  which  it  grows,  and  there- 
fore similar  excessive  heating  of  the  air  over  the 
land,  by  the  greatly  extended  surface  the  trees  and 
undergrowth  present  to  the  sun's  rays,  but  it  also 
acts  by  the  direct  absorption  of  the  sun's  rays 
to  cause  the  separation  of  the  carbon  from  the 
oxygen  in  carbonic  acid,  and  the  hydrogen  from 

the   oxygen  in  the  water  in  the  vegetable  king- 

12 


134  OUTLINES  OF  FORESTRY. 

dom.     Tyndall,  in  his  "  Heat  as  a  Mode  of  Mo- 
tion," *  page  529,  says  : 

"  In  the  building  of  plants,  carbonic  acid  is  the  material 
from  which  the  carbon  of  the  plant  is  derived,  while  water  is 
the  substance  from  which  it  obtains  its  hydrogen.  The  solar 
rays  wind  up  the  weight.  They  sever  the  united  atoms,  set- 
ting the  oxygen  free,  and  allowing  the  carbon  and  the  hydro- 
gen to  aggregate  in  woody  fibre.  If  the  sun's  rays  fall  upon 
a  surface  of  sand,  the  sand  is  heated,  and  finally  radiates 
away  as  much  heat  as  it  receives.  Let  the  same  rays  fall  upon 
a  forest ;  then  the  quantity  of  heat  given  back  is  less  than 
that  received,  for  a  portion  of  the  sunlight  is  invested  in  the 
building  of  the  trees.  We  have  already  seen  how  heat  is  con- 
sumed in  forcing  asunder  the  atoms  of  bodies,  and  how  it 
reappears  when  the  attraction  of  the  separated  atoms  comes 
again  into  play.  The  precise  considerations  which  we  then 
applied  to  heat,  we  have  now  to  apply  to  light,  for  it  is  at  the 
expense  of  the  solar  light  that  the  chemical  decomposition 
takes  place.  Without  the  sun,  the  reduction  of  the  carbonic 
acid  and  water  cannot  be  effected ;  and,  in  this  act,  an  amount 
of  solar  energy  is  consumed,  exactly  equivalent  to  the  molecu- 
lar work  done." 

Concerning  the  influence  of  the  forests  on  cli- 
mate, Hough,  in  his  report  to  the  United  States 

*  Eeprinted,  by  permission,  from  "  Heat  as  a  Mode  of 
Motion,"  by  John  Tyndall,  F.K.S.,  LL.D.  New  York: 
D.  Appleton  &  Company,  5  Bond  Street,  1883.  Pp.  591. 


CLIMATE  AS  INFLUENCED  BY  THE  FOREST.      135 

Commissioners  of  Forestry  for  1877,  quoting  from 
a  paper  by  M.  A.  C.  Becquerel,  on  the  "  Climatic 
Effects  of  Forests,"  *  page  310,  says : 

"  The  forests  exercise  in  many  ways  an  influence  upon  the 
climate,  but  to  understand  this  we  must  define  what  we  under- 
stand by  climate. 

"  The  climate  of  a  country,  according  to  M.  Humboldt,  is 
the  combination  of  calorific,  aqueous,  luminous,  aerial,  electri- 
cal, and  other  phenomena,  which  fix  upon  a  country  a  definite 
meteorological  character  that  may  be  different  from  that  of 
another  country  under  the  same  latitude  and  with  the  same 
geological  conditions.  According  as  one  or  another  of  these 
phenomena  predominate  we  call  the  climate  warm,  cold,  or 
temperate,  dry  or  humid,  calm  or  windy. 

"  We  always  regard  heat  as  exercising  the  greatest  influence, 
and  after  this  the  amount  of  water  falling  in  different  seasons 
of  the  year,  the  humidity  or  dryness  of  the  air,  prevailing 
winds,  number  and  distribution  of  storms  throughout  the  year, 
clearness  or  cloudiness  of  the  sky,  the  nature  of  the  soil  and 
vegetation  which  covers  it,  and,  according  as  it  is  natural  or 
the,  result  of  cultivation,  the  following  questions  arise  for 
consideration : 

"  1.  What  is  the  part  that  forests  play  as  a  shelter  against 
the  winds  or  as  a  means  of  retarding  the  evaporation  of  rain- 
water ? 

*  Reprinted,  by  permission,  from  a  "  Report  upon  Forestry," 

1877,  by  Franklin  B.   Hough.    Washington  Printing-Oflice, 

1878.  Pp.650. 


136  OUTLINES  OF  FORESTRY. 

"  2.  What  influence  do  the  forests  exert,  through  the  absorp- 
tion of  their  roots  or  the  evaporation  of  their  leaves,  in  modi- 
fying the  hygrometrical  conditions  of  the  surrounding  atmos- 
phere ? 

"  3.  How  do  they  modify  the  temperature  of  a  country  ? 

"  4.  Do  the  forests  exercise  an  influence  on  the  amount  of 
water  falling,  and  upon  the  distribution  of  rain  throughout 
the  year,  as  well  as  upon  the  regulation  of  running  waters  and 
springs  ? 

"  5.  In  what  manner  do  they  intervene  in  the  preservation  of 
mountains  and  slopes  ? 

"  6.  Do  the  forests  serve  to  draw  from  the  storm-clouds  their 
electricity,  and  by  thus  doing  diminish  their  effects  upon  the 
neighboring  regions  not  wooded  ? 

"  7.  What  is  the  nature  of  the  influence  that  they  may  be 
able  to  exercise  upon  the  public  health  ? 

"  From  these  questions  we  may  see  what  questions  we  must 
solve  before  being  able  to  decide  as  to  the  influence  that  the 
clearing  off  of  woodlands  may  exercise  upon  the  climate  of  a 
country." 

Much  valuable  data  concerning  the  results  of 
the  destruction  of  the  forests  on  climate,  rainfall, 
and  other  meteorological  conditions,  were  collected 
by  several  scientific  expeditions  sent  to  Brazil 
under  the  direction  of  Louis  Agassiz. 

In  an  account  of  the  Thayer  expedition  in  1865 
and  1866,  Professor  Hartt,  in  a  description  of  the 
"  Geology  and  Physical  Geography  of  Brazil,"  * 
page  319,  thus  refers  to  the  marked  effects  that  have 


CLIMATE  AS  INFLUENCED  BY  THE  FOREST.      137 

been  produced  by  the  wholesale  destruction  of  the 
forests  by  the  burning  over  of  their  former  areas, — 

"  The  limits  of  the  forests,  of  the  belt  of  decomposition, 
and  of  the  area  over  which  copious  rains  fall,  coincide  very 
remarkably,  and  show  a  dependence  upon  each  other,  but  the 
forest  belt  has  a  smaller  area  than  that  of  decomposition  or  of 
the  rains.  The  wooded  belt  seems  to  have  narrowed  greatly 
within  comparatively  recent  times,  losing  its  foothold  in  the 
west,  where  immense  regions,  now  campos,  over  which  the 
climate  and  soil  would  normally  be  proper  for  the  growth  of 
forests,  have  dried  up,  the  climate  has  become  hot,  less  rain 
now  falls,  and  the  forest  cannot  regain  its  lost  place.  Doubt- 
less there  are  many  natural  physical  causes  to  be  taken  into 
consideration  in  studying  the  distribution  of  the  forest,  catinga, 
and  campos  florae ;  but  there  is  one  agency  that  has  been  at 
work  in  Brazil  whose  effects  we  can  hardly  over-estimate,  and 
that  is  the  burning  over  of  the  wood  and  campos  lands  by 
man.  The  very  physical  features  of  the  highlands  of  Brazil 
determine  a  difference  in  the  luxuriance  in  the  florae  of  differ- 
ent regions,  and  there  are,  as  I  have  already  shown,  regions 
where  for  ages  the  climate  has  been  such  that  forests  could 
scarcely  have  had  any  noteworthy  extension,  so  that  there  must 
have  always  been  in  Brazil,  naturally,  virgin  forests,  catingas, 
campos,  and  barrens.  On  the  coast,  where  the  forest  is  dense 
and  moist,  and  the  climate  is  wet,  forest  fires  are  next  to 

*  Eeprinted,  by  permission,  from  "  Scientific  Results  of  a 
Journey  in  Brazil,"  by  Ch.  Fred.  Hartt.  Boston :  Field,  Os- 
good  &  Co.,  1870.  Pp.  620. 

12* 


138  OUTLINES  OF  FORESTRY. 

impossible,  and  one  never  sees  a  scorched  and  dead  wood,  such 
as  covers  so  large  an  area  in  the  province  of  New  Brunswick, 
for  instance.  But  in  the  interior,  where  the  catinga  forests 
drop  their  leaves,  and  are  dead  for  several  months  in  the  dry 
season,  fires  are  easily  kindled  and  the  wood  killed;  and 
fires  set  in  open  fields  or  campos,  for  the  purpose  of  pro- 
ducing a  new  crop  of  grass,  may  spread  to  the  neighboring 
catingas.  It  is  the  opinion  of  many  writers  that  a  large  part 
of  the  catinga  and  campos  regions  of  the  Brazilian  highlands 
was  once  covered  by  forests,  and  that  their  present  bare  ap- 
pearance and  the  character  of  their  florae  is  in  a  very  great 
measure  due  to  frequent  and  extensive  burning  over  of  the 
country.  Every  year  the  Brazilian  campos  lands  are  sys- 
tematically and  almost  entirely  burned  over,  for  the  purpose 
of  producing  a  new  crop  of  grass.  This  burning,  of  course, 
has  destroyed  all  those  trees  and  shrubs  and  plants  of  all 
kinds  that  cannot  bear  the  scorching,  and  has  wrought  a  great 
alteration  in  the  character  of  the  whole  flora  of  the  region  ; 
the  climate  also  has  suffered  a  change,  for  with  the  destruction 
of  the  woods  and  forests  it  becomes  hotter,  the  unprotected 
earth  is  like  a  furnace,  streams  run  diy  a  few  days  after  a 
shower,  and  the  springs  disappear." 

The  following  geographical  instances  of  the 
effects  of  forests  on  climate  are  referred  to  by 
Becquerel  in  a  previous  quotation.* 

*  Eeprinted,  by  permission,  from  "  Keport  upon  Forestry," 
1877,  by  Franklin  B.  Hough.  Washington :  Government 
Printing-Office,  1878. 


CLIMATE  AS  INFLUENCED  BY  THE  FOREST.      139 

ST.  HELENA. 

Fully  forested  when  discovered  in  1502.  The  introduction 
of  goats  and  other  causes  led  to  the  removal  of  its  forests. 
Heavy  floods  and  severe  droughts  were  the  result ;  replanting 
of  forest  trees  towards  the  close  of  1700  resulted  in  a  more 
uniform  rainfall  and  its  better  distribution.  Subsequent  de- 
structions of  the  forest  have  again  brought  back  the  original 
condition  of  affairs. 

ISLAND  OF  ASCENSION. 

When  discovered  in  1815  it  was  barren,  and  so  destitute 
of  water  that  supplies  were  brought  to  it  from  the  mainland. 
The  effects  of  planting  trees  resulted  in  an  increased  rainfall, 
from  10.18  in  1858  to  25.11  in  1863.  It  now  grows  forty  kinds 
of  trees,  where  but  one  grew  in  1843  for  want  of  water. 


140  OUTLINES  OF  FORESTRY. 


XIV.    PURIFICATION    OF  THE   ATMOS- 
PHERE. 

THE  atmosphere  covers  the  earth's  surface  as  a 
vast  ocean  of  air  that  extends  upwards  for  a  dis- 
tance of  several  hundred  miles. 

It  is  composed  mainly  of  a  mixture  of  two  gas- 
eous substances, — namely,  of  nearly  seventy-seven 
per  cent,  by  weight  of  nitrogen  and  about  twenty- 
three  per  cent,  of  oxygen.  Besides  these  there  is 
a  nearly  constant  quantity  of  carbonic  acid  gas, 
and  a  variable  quantity  of  the  vapor  of  water. 

The  carbonic  acid  is  nearly  in  the  proportion  of 
four  parts  to  ten  thousand  of  air ;  or  very  nearly 
one  cubic  inch  of  carbonic  acid  gas  to  each  cubic 
foot  of  ordinary  air. 

The  different  ingredients  of  the  atmosphere 
serve  various  purposes  in  the  economy  of  the 
earth. 

The  oxygen  is  necessary  for  the  existence  of 
animal  life. 

The  carbonic  acid  is  necessary  for  the  existence 
of  plant  life. 


PURIFICATION  OF  THE  ATMOSPHERE.       141 

The  moisture  of  the  air  is  necessary  for  the 
existence  of  both  animal  and  plant  life,  although, 
perhaps,  it  is  more  necessary  for  the  existence  of 
plant  life. 

Every  action  of  an  animal  results  in  the  decay 
and  subsequent  death  of  some  part  of  its  body. 
Although  this  death  does  not  take  place  immedi- 
ately, yet  the  us*e  of  any  part  or  member  of  the 
body  results  in  its  waste  and  subsequent  death. 
In  order  to  replace  these  dead  parts  some  form 
of  nourishment  is  necessary.  This  nourishment 
comes  from  the  food  of  the  animal,  which,  by  the 
process  of  digestion,  goes  to  make  up  the  blood. 
The  blood  carries  to  the  parts  of  the  body  which 
require  nourishment  the  materials  needed  for  sub- 
sequent growth,  and,  at  the  same  time,  takes  away 
or  carries  off  the  dead  or  decaying  parts. 

The  blood  is  forced  through  the  different  parts 
of  the  body  by  the  action  of  the  heart,  which  acts 
like  a  force-pump.  The  blood  goes  to  these  parts 
of  the  body  as  bright  red  arterial  blood.  It  leaves 
them  so  clogged  with  dead  and  decaying  parts, 
that  it  becomes  changed  into  a  dark,  bluish-black, 
venous  blood. 

The  oxygen  of  the  air  is,  in  general,  necessary 
to  the  existence  of  animal  life  in  order  to  burn 


142  OUTLINES  OF  FORESTRY. 

out  or  remove  from  the  blood  these  dead  and 
decaying  parts,  and  so  change  the  dark,  venous 
blood  to  bright  red  arterial  blood. 

The  oxygen  brings  about  this  change  mainly  by 
combining  with  and  slowly  burning  the  waste 
products  so  as  to  form  water  vapor  and  carbonic 
acid  gas. 

If  there  was  nothing  to  oppose  this  action  of 
animal  life  all  the  oxygen  would,  in  the  end,  be 
removed  from  the  air  and  changed  into  carbonic 
acid  gas,  and  no  further  animal  life  would  be  pos- 
sible on  the  earth.  Plants,  however,  during  their 
growth,  in  the  presence  of  sunshine,  take  in  or 
absorb  carbonic  acid  gas.  In  the  delicate  structure 
of  the  leaf  this  gas  is  broken  up  into  carbon, 
which  is  retained  by  the  plant  to  form  its  woody 
fibre,  and  into  oxygen,  which  is  given  off  and 
passes  into  the  atmosphere. 

Plants,  therefore,  during  active  growth  take  in 
carbonic  acid  gas  and  give  out  oxygen. 

A  wonderful  balance  is  thus  maintained  in  na- 
ture, and  the  composition  of  the  atmosphere  is 
kept  practically  constant. 

What  animals  reject,  plants  need  for  their  ex- 
istence. What  plants  reject,  animals  need  for  their 
existence.  It  is  like  the  case  of  the  renowned 


PURIFICATION  OF  THE  ATMOSPHERE.       143 

Jack  Sprat  and  his  wife,  of  nursery  lore,  who 
between  them  kept  both  plate  and  platter  clean. 
Each  liked  and  thrived  on  what  the  other  re- 
jected. 

If  this  balance  between  the  plant  and  animal 
kingdom  is  disturbed,  the  composition  of  the 
atmosphere  will  be  altered,  and  a  marked  change 
will  be  produced  in  the  earth's  plant  and  ani- 
mal life.  Such  changes  have  been  observed  in 
the  geological  past  long  before  the  creation  of 
man. 

The  earth's  atmosphere  was  originally  vaster 
than  at  present.  The  quantity  of  oxygen  and 
carbonic  acid  gas  was  enormously  greater. 

A  careful  estimate  places  the  amount  of  oxygen 
that  exists,  combined  with  the  different  substances 
that  form  the  fifteen  or  twenty  miles  of  the  earth's 
crust  that  have  been  carefully  studied,  at  least  at 
one-half  of  the  total  weight. 

At  an  early  age  in  the  earth's  life  this  oxygen 
existed  in  a  free  state  in  the  atmosphere,  and  be- 
came fixed  by  combining  with  or  oxidizing  the 
different  materials  of  the  crust.  This  oxidizing 
action  has  now  practically  ceased,  and  the  quantity 
of  oxygen  present  in  the  air  is  constant. 

Prior  to  the  Carboniferous   age  carbonic   acid 


144  OUTLINES  OF  FORESTRY. 

must  have  existed  in  the  air  in  enormous  quanti- 
ties ;  for,  the  vast  deposits  of  carbon,  which  form 
the  coal-beds  now  found  in  the  different  parts  of 
the  crust,  then  existed  in  a  gaseous  condition  in 
the  atmosphere  combined  with  oxygen. 

Animal  life  of  the  present  type  was  impossible 
in  the  unpurified  atmosphere  that  existed  before 
the  Carboniferous  age.  The  conditions  were,  how- 
ever, such  as  to  favor  dense  and  luxuriant  plant 
life,  and  at  no  time  in  the  world's  history,  either 
before  or  since,  has  such  luxuriant  vegetable 
growth  existed. 

A  twofold  action  of  purification  was  effected  by 
the  plants  of  the  Carboniferous  period ;  namely, 
the  separation  of  the  carbon  and  the  liberation  of 
the  oxygen. 

The  exact  balance  between  the  plant  and  ani- 
mal life  of  the  earth,  so  carefully  established 
by  nature,  cannot  be  disturbed  without  marked 
changes  in  the  entire  races  of  animals  and  plants 
that  now  exist. 

The  thoughtless  and  unnecessary  removal  of  the 
forests  from  over  extended  areas  will  not  only  dis- 
turb the  balance  during  the  time  such  surfaces  are 
bare,  but  since,  in  many  cases,  such  removal  per- 
mits this  section  of  country  to  be  denuded  of  its 


PURIFICATION  OF  THE  ATMOSPHERE.       145 

Boil,  there  will  also  follow  a  permanent  disturbance 
from  the  inability  of  such  section  of  country  to 
sustain  any  plant  life. 

As  to  the  purification  of  the  atmosphere  by 
plants,  Dana,  in  his  "  Manual  of  Geology,"  *  says, 
on  page  353, — 

"  In  the  present  era,  the  atmosphere  consists  essentially  of 
oxygen  and  nitrogen,  in  the  proportion  of  twenty-three  to 
seventy-seven  parts  by  volume.  Along  with  these  constitu- 
ents, there  are  about  four  parts  by  volume  of  carbonic  acid  in 
ten  thousand  parts  of  air.  Much  more  carbonic  acid  would 
be  injurious  to  animal  life.  To  vegetable  life,  on  the  contrary, 
it  would  be,  within  certain  limits,  promotive  to  growth ;  for 
plants  live  mainly  by  means  of  the  carbonic  acid  they  receive 
through  their  leaves.  The  carbon  they  contain  comes  princi- 
pally from  the  air. 

"  This  being  so,  it  follows,  as  has  been  well  argued,  that  the 
carbon  which  is  now  coal,  and  was  once  in  plants  of  different 
kinds,  has  come  from  the  atmosphere,  and,  therefore,  that  the 
atmosphere  now  contains  less  carbonic  acid  than  it  did  at  the 
beginning  of  the  Carboniferous  period,  by  the  amount  stowed 
away  in  the  coal  of  the  globe. 

******** 

"  Such  an  atmosphere,  containing  an  excess  of  carbonic  acid 
as  well  as  of  moisture,  would  have  had  greater  density  than 

*  Reprinted,  by  permission,  from  a  "  Manual  of  Geology," 
third  edition,  by  James  D.  Dana.    New  York :  Ivison,  Blake- 
man,  Taylor  &  Co.     London  :  Trubner  &  Co.    Pp.  911. 
a        k  13 


146  OUTLINES  OF  FORESTRY. 

the  present ;  consequently,  as  urged  by  E.  B.  Hunt,  it  would 
have  occasioned  increased  heat  at  the  earth's  surface,  and  this 
would  have  been  one  cause  of  a  higher  temperature  over  the 
globe  than  the  present. 

"  During  the  progress  of  the  Carboniferous  period  there  was, 
then,  (1)  a  using  up  and  storing  away  of  the  carbon  of  the 
superfluous  carbonic  acid,  and,  thereby,  (2)  a  more  or  less  per- 
fect purification  of  the  atmosphere,  and  a  diminution  of  its 
density.  In  early  time  there  was  no  aerial  life  on  the  earth ; 
and,  so  late  as  the  Carboniferous  period,  there  were  only  rep- 
tiles, myriapods,  spiders,  insects,  and  pulmonate  mollusks. 
The  cold-blooded  reptiles  of  low  order  of  vital  activity,  cor- 
respond with  these  conditions  of  the  atmosphere.  The  after- 
ages  show  an  increasing  elevation  of  grade  and  variety  of 
type  in  the  living  species  of  the  land." 


HAIL.  147 


XV.    HAIL. 

HAIL  occurs  at  times  when  great  differences  of 
temperature  exist  between  neighboring  masses  of 
very  moist  air. 

By  permitting  great  differences  of  temperature 
to  occur,  the  destruction  of  the  forest  is,  in  many 
cases,  followed  by  an  increase  in  the  number  and 
severity  of  hail-storms. 

In  order  to  understand  the  manner  in  which  the 
destruction  of  the  forest  may  influence  the  occur- 
rence of  hail-storms,  it  will  be  necessary  to  study 
some  of  the  peculiarities  of  such  storms  and  to  re- 
view what  are  now  generally  believed  to  be  their 
causes. 

Although  hail  may  fall  at  any  time  of  the  year, 
yet  it  occurs  most  frequently  in  summer  towards 
the  close  of  a  very  warm  day. 

The  exact  causes  which  produce  hail  are  not 
known.  The  conditions  necessary  for  its  occur- 
rence appear  to  be  the  rapid  mixture  of  very  warm 
and  very  cold  moist  air. 

A  hail-storm  is  generally  preceded  by  the  appear- 


148  OUTLINES  OF  FORESTRY. 

ance  of  several  layers  of  dark,  grayish  clouds.  In 
most  all  cases,  before  the  beginning  of  a  hail-storm, 
a  violent  movement  is  seen  to  take  place  between 
these  layers,  apparently  of  a  whirling  character. 
Generally,  too,  hail-storms  are  attended  by  violent 
disturbances  in  the  electrical  equilibrium  of  the 
atmosphere,  as  is  evidenced  by  the  frequent  dis- 
charge of  the  lightning-bolt  and  the  almost  con- 
tinual roar  of  thunder.  Then  follows  a  fall  of 
hailstones,  the  size  of  which  is  much  larger  at  the 
beginning  and  towards  the  middle  of  the  storm 
than  towards  the  close.  Towards  the  close  of  the 
storm,  however,  the  quantity  of  hail  which  falls  is 
greatest. 

If  a  hailstone  be  examined  by  cutting  it  in  two, 
it  will  be  seen  to  consist  of  alternate  layers  of  ice 
and  snow  laid  over  one  another  in  successive  coats 
like  the  layers  of  an  onion.  A  cross-section  of  a 
hailstone  can  be  made  by  holding  it  against  the 
surface  of  a  hot  plate  until  half  of  the  stone  has 
been  melted  away. 

Hailstones  vary  in  weight  from  a  few  grains  to 
several  pounds.  Records  exist  of  hailstones  weigh- 
ing many  pounds,  sometimes  of  even  several  hun- 
dred pounds.  In  such  cases,  however,  it  is  more 
than  probable  that  the  stones  were  produced  by 


HAIL.  149 

the  regelation,  or  freezing  together,  of  numerous 
smaller  stones,  as  follows  : 

The  excessive  fall  of  small  hailstones,  that  oc- 
curs towards  the  close  of  the  storm,  often  produces 
heaps  of  hailstones  several  feet  in  thickness.  The 
separate  hailstones  readily  freeze  together,  and  are 
afterwards  cut  into  smaller  masses  by  the  action 
of  the  water  rapidly  draining  off  the  earth.  The 
fragments  thus  formed,  in  all  probability,  give  rise 
to  stories  of  mammoth  hailstones. 

The  severity  of  the  lightning-flashes,  which  at- 
tend nearly  all  great  hail-storms,  has  led  some 
meteorologists  to  believe  that  hail-storms  are  caused 
by  the  presence  of  an  unusual  quantity  of  free  elec- 
tricity in  the  atmosphere.  The  electrical  theory 
of  hail  is,  however,  at  the  present,  almost  entirely 
discarded,  it  being  now  generally  recognized  that 
the  lightning  is  the  effect  of  the  hail-storm,  and 
not  its  cause. 

Yolta  proposed  the  following  electrical  theory 
for  the  production  of  hail.  He  imagined  two 
approximately  parallel  clouds  near  together,  the 
upper  cloud  formed  of  snow,  and  the  under  cloud 
of  rain.  Assuming  these  clouds  to  be  respectively 
charged  with  positive  and  negative  electricity,  the 
particles  of  snow  in  the  snow-cloud  might,  he 

13* 


150  OUTLINES  OF  FORESTRY. 

assumed,  be  alternately  attracted  and  repelled  into 
and  from  the  rain-cloud,  and  thus  receive  alternate 
coatings  of  ice  and  snow  until  they  finally  fell  to 
the  ground  as  hailstones. 

In  France,  where  the  reckless  destruction  of  the 
forest  has  been  attended  by  a  marked  increase  in 
the  number  and  severity  of  hail-storms,  miniature 
lightning-rods  have  been  erected  in  the  fields  to 
prevent  the  occurrence  of  hail-storms.  These 
lightning-rods  either  took  the  shape  of  captive 
balloons  secured  to  the  earth  by  tinsel  threads,  or 
of  bundles  of  straw  set  upright  in  the  field,  or  of 
metal  rods  permanently  connected  with  the  ground. 
Their  object  was  to  gradually  discharge  the  air  of 
its  free  electricity,  and  thus  prevent  the  occurrence 
of  hail-storms.  The  name  of  such  rods,  paragreles, 
is  significant  of  their  supposed  action.  Unfortu- 
nately, they  have  proved  futile  in  action,  since  again 
and  again  the  portions  provided  with  this  supposed 
protection  have  been  as  severely  visited  by  hail- 
storms as  unprotected  portions. 

An  endeavor  has  been  made  to  explain  the 
peculiar  shape  of  hailstones  by  the  existence  of 
a  number  of  approximately  parallel  clouds  com- 
posed alternately  of  snow  and  rain.  Drops  of 
rain  falling  from  the  upper  cloud  would  thus 


HAIL.  151 

receive  successive  coatings  of  snow  and  ice  as  they 
passed  successively  through  the  snow-  and  rain- 
clouds,  and  would  finally  fall  as  characteristically- 
shaped  hailstones. 

The  theory  now  generally  received  in  regard  to 
the  formation  of  hailstones  is,  that  in  such  storms 
the  wind  rotates  around  a  vertical  rather  than 
around  a  horizontal  axis.  If  such  a  whirling  mo- 
tion exists  between  a  neighboring  rain-  and  snow- 
cloud,  the  particles  of  snow  would  be  successively 
dipped  into  the  rain-  and  snow-clouds,  and  would 
thus  receive  alternate  layers  of  ice  and  snow. 

A  somewhat  similar  theory  regards  a  hail-storm 
as  belonging  to  the  type  of  the  ordinary  tornado. 
The  whirling  motion  of  the  air  is  supposed  to 
produce  the  alternate  coatings  of  ice  and  snow  by 
the  alternate  exposure  of  the  moisture  to  the  dif- 
ferent temperatures  found  in  the  denser  and  rarer 
portions  of  the  space  around  which  the  wind  is 
whirling. 

Hail-storms  often  cause  great  damage.  A  single 
hail-storm  in  France  has  been  known  to  cause  loss 
to  the  agricultural  districts  amounting  to  the  sum 
of  at  least  one  million  pounds  sterling. 

Although  the  exact  cause  of  hail-storms  is  at 
present  unknown,  yet  the  storms  never  occur 


152  OUTLINES  OF  FORESTRY. 

unless  marked  differences  of  temperature  exist 
between  neighboring  portions  of  the  air.  The 
removal  of  the  forest  from  any  considerable  section 
of  country  permits  such  differences  of  tempera- 
ture to  occur.  In  point  of  fact,  it  has  been  no- 
ticed in  parts  of  the  world  from  which  the  forests 
have  been  removed,  that  the  number  and  severity 
of  hail-storms  have  undoubtedly  increased. 

Destructive  hail-storms  may  therefore  be  re- 
garded as  one  of  the  evil  results  which  naturally 
follow  the  destruction  of  the  forest. 

As  regards  the  supposed  protective  influence 
of  lightning-  or  hail-rods  against  destructive  hail- 
storms, Loomis,  in  his  "  Treatise  on  Meteorology,"  * 
writes  on  page  135  : 

"  It  has  been  proposed  to  preserve  the  vineyards  and  valua- 
ble farms  from  the  ravages  of  hail  by  erecting  an  immense 
number  of  poles,  armed  with  iron  points,  communicating  with 
the  earth,  for  the  purpose  of  drawing  off  the  electricity  of  the 
clouds.  Multitudes  of  these  hail-rods  were  erected  in  Switzer- 
land, but  without  the  expected  success. 

"  It  is  believed  that  electricity  performs  altogether  a  subordi- 
nate, if  not  an  unimportant  part  in  the  formation  of  hail ; 

*  Reprinted,  by  permission,  from  "  A  Treatise  on  Meteo- 
rology," by  Elias  Loomis,  LL.D.  New  York:  Harper  & 
Brothers,  Franklin  Square,  1868.  Pp.  305. 


HAIL.  153 

and  if  we  could  draw  off  all  the  electricity  from  the  hail-cloud 
as  fast  as  it  was  generated,  it  is  not  improbable  that  the  hail 
would  be  formed  about  as  large  and  as  abundantly  as  at  present. 
"  But,  even  supposing  electricity  to  be  the  sole  agent  in  the 
production  of  hail,  hail-rods  could  not  be  expected  to  furnish 
security  against  hail  unless  an  entire  continent  could  be  studded 
thick  with  them,  for  in  the  middle  latitudes  the  hail-cloud  ad- 
vances eastward  with  a  velocity  sometimes  of  forty  or  more  miles 
per  hour,  and  the  hailstones  which  fall  in  one  locality  are  those 
which  were  forming  when  the  cloud  was  many  miles  westward 
of  that  point ;  so  that,  to  protect  a  small  spot,  the  whole  coun- 
try for  many  miles  westward  should  be  armed  with  rods ;  and 
it  is  conceivable  that  a  hail-cloud  arriving  over  a  region  studded 
with  these  rods  might  immediately  pour  down  a  large  quantity 
of  hailstones  which  would  have  fallen  farther  eastward  if  the 
rods  had  not  discharged  the  electricity  of  the  cloud." 

The  following  description  of  a  hail-storm  that 
occurred  near  Bordeaux,  France,  in  1865,  is  thus 
given  by  Flammarion,  in  his  work  entitled  "  The 
Atmosphere,"  *  page  393. 

"  On  May  9,  1865,  for  instance,  a  storm  began  at  8.30  A.M. 
over  Bordeaux  and  proceeded  in  a  N.N.E.  direction,  passing 
over  Perigueux  at  10  A.M.,  Limoges  at  noon,  Bourges  at  2 
P.M.,  Orleans  at  5.30  P.M.,  Paris  at  7.45  P.M.,  Laon  at  11  P.M., 
and  collapsing  a  little  after  midnight  in  Belgium  and  the  North 

*  Reprinted,  by  permission,  from  "  The  Atmosphere,"  by 
Chamille  Flammarion.  New  York:  Harper  &  Brothers, 
Franklin  Square,  1873.  Pp.  454. 


154  OUTLINES  OF  FORESTRY 

Sea.  Its  mean  breadth  was  from  fifteen  to  twenty  leagues. 
The  hail  only  fell  in  certain  places  :  to  the  left  of  Perigueux, 
over  the  arrondissement  of  Limoges,  to  the  right  of  Chateau- 
roux,  to  the  southeast  of  Paris,  from  Corbeil  to  Lagny,  and  in 
the  arrondissements  of  Soissons  and  Saint-Quentin.  At  this 
latter  point  it  was  of  a  formidable  character.  The  crystal  mass 
which  fell  from  the  sky  upon  the  Catelet  meadows  formed  a 
bed  a  mile  and  a  quarter  long  and  two  thousand  feet  broad, 
estimated  to  amount  altogether  to  twenty-one  millions  of  cubic 
feet.  The  hailstones  did  not  disappear  for  more  than  four 
days  afterwards.  These  hailstones  sometimes  destroy  all  the 
crops,  as,  for  instance,  that  which  occurred  in  the  neighbor- 
hood of  Angouleme  on  August  3,  1813.  The  day  had  been 
fine,  and  the  wind  was  due  north  until  3  P.M.,  when  it  sud- 
denly veered  right  round ;  the  sky  gradually  became  covered 
with  clouds,  which,  collecting  one  on  the  top  of  the  other, 
offered  a  terrible  spectacle.  The  wind,  which  from  noon  until 
5  P.M.  had  been  rather  violent,  suddenly  dropped.  Thunder 
was  heard  in  the  distance,  and  gradually  became  louder ;  the 
sky,  at  last,  became  totally  obscured,  and  at  6  P.M.  there  was 
a  tremendous  fall  of  hail,  the  stones  being  as  large  as  eggs. 
Several  persons  were  severely  wounded,  and  a  child  was  killed 
near  Barbezieux.  The  next  day  the  ground  looked  as  it  might 
do  in  midwinter :  the  hailstones  had  accumulated  in  the  hol- 
lows and  the  roads  to  a  height  of  thirty  to  forty  inches ;  trees 
were  entirely  stripped  of  their  leaves ;  vines  were  cut  into 
pieces,  the  crops  crushed,  the  cattle,  sheep,  and  pigs  especially 
were  severely  injured.  The  whole  neighborhood  was  deprived 
of  game,  and  some  few  young  wolves  were  found  dead.  The 
effects  of  the  storm  were  still  visible  in  1818."  "  * 


REFORESTATION  AND   TREE-PLANTING.      155 


XVI.  REFORESTATION  AND  TREE- 
PLANTING. 

BY  reforestation  is  meant  the  replanting  of  trees 
in  any  locality  from  which  they  have  been  removed 
either  accidentally  or  purposely. 

Where  the  removal  of  the  forests  has  been 
made  in  a  hap-hazard  way,  and  no  care  has  been 
taken  to  protect  the  soil  from  the  effects  of  rapid 
drainage,  the  loss  of  the  soil  in  some  cases  is  so 
great  as  to  render  the  area  not  only  unable  to  sus- 
tain trees  of  the  same  character  as  those  which 
have  been  removed,  but  even  to  render  it  unable 
to  sustain  any  trees  whatever.  If,  however,  in  the 
removal  of  the  trees,  care  has  been  taken  that  the 
loss  of  soil  is  but  trifling,  it  may  be  possible  to 
again  reclothe  the  surface  with  trees  similar  to 
those  which  have  been  removed. 

The  French  term  for  this  process  of  replacing 
forests  is  reboisement.  Our  English  word  reforesta- 
tion may  be  safely  taken  as  its  equivalent. 

The  object  of  reforestation  is  to  avoid  the  evils 
which  result  from  the  removal  of  the  forests  by 


156  OUTLINES  OF  FORESTRY. 

perpetually  maintaining  forest  tracts  in  portions 
of  the  earth  set  aside  for  such  purposes. 

Where  the  loss  of  the  soil  following  the  destruc- 
tion of  the  forests  has  been  too  marked  to  permit 
the  successful  replanting  of  trees,  some  of  the  evil 
effects  following  rapid  drainage,  such,  for  exam- 
ple, as  disastrous  floods,  with  their  consequent 
droughts,  have  been  in  a  measure  lessened  by  re- 
planting the  bare  surface  with  different  species  of 
hardy  grasses,  which,  by  absorbing  and  holding 
the  rain,  permit  the  water  to  drain  slowly  off  the 
surface. 

The  time  required  for  the  full  growth  of  forest 
trees  is  so  great  that,  unless  considerable  encour- 
agement is  given  to  the  planting  of  trees,  reforesta- 
tion will  scarcely  be  attempted  to  any  considerable 
extent.  In  most  cases  where  reforestation  has  been 
attempted,  laws  have  been  enacted  offering  certain 
premiums,  either  in  land  or  in  money,  for  success- 
ful tree-planting. 

Where  reforestation  is  carried  out  on  a  large 
scale,  under  the  encouragement  of  a  government,  it 
is  desirable  that  either  seeds  or  seedlings  be  sup- 
plied by  the  government,  or  that  extensive  nur- 
series be  established.  Great  care  must  be  taken 
to  insure  the  planting  of  the  varieties  of  trees  best 


REFORESTATION  AND   TREE-PLANTING.      157 

suited  to  exist  in  the  particular  section  of  country 
that  is  to  be  reforested. 

Since  those  sections  of  country  where  reforesta- 
tion is  to  be  attempted  have  already,  by  the  removal 
of  the  forests,  been  exposed  to  the  loss  of  soil, 
great  care  must  be  taken  in  the  replanting  of  trees 
not  to  needlessly  disturb  the  soil.  Two  methods 
may  be  employed  in  reforestation, — viz. : 

1.  Sowing. 

2.  Tree-planting. 

Considerable  difference  of  opinion  exists  as  to 
which  of  these  two  methods  is  preferable.  Un- 
questionably, however,  each  is  best  suited  for  par- 
ticular cases,  and,  in  point  of  fact,  each  has  been 
adopted  with  considerable  success  in  different  parts 
of  the  world. 

Seeding  can,  perhaps,  be  most  profitably  fol- 
lowed in  the  temperate  latitudes,  in  situations 
where  the  growth  of  the  tree  is  comparatively 
certain.  In  higher  latitudes  the  planting  of  trees 
is,  perhaps,  preferable,  since  the  germination  and 
continued  growth  of  the  seeds  are  by  no  means  so 
certain. 

In  the  case  of  the  destruction  of  the  forest  by 
avalanches,  replanting  or  reforestation  is  rendered 
much  more  difficult  by  the  fact  that  the  soil,  in 

14 


158  OUTLINES  OF  FORESTRY. 

such  cases,  is  often  so  almost  entirely  removed  by 
the  force  of  the  rushing  snow  that  little  but  the 
bare  rocks  remain. 

In  Italy,  laws  passed  in  1877,  set  aside  the  fol- 
lowing classes  of  lands  as  suitable  for  being  in- 
cluded under  the  provisions  of  the  forest  regula- 
tions,— namely : 

Forest  lands  on  mountain-sides,  or  in  such 
places  as  might,  from  their  location,  by  the  loss  of 
their  trees,  cause  injury  to  the  lowlands  by  ava- 
lanches, or  that  might,  by  their  drainage,  influence 
or  modify  the  water-courses. 

It  is  generally  recognized  in  some  of  the  west- 
ern portions  of  the  United  States,  that  when  trees 
are  planted  in  plots  around  the  farm  lands,  or  on 
the  sides  of  such  lands,  the  protection  thus  af- 
forded the  rest  of  the  land  against  the  winds  is 
greater  in  actual  money  value  than  the  rent  of  the 
ground  occupied  by  such  forests. 

Whenever  reforestation  is  attempted  over  ex- 
tended areas,  care  should  be  taken  as  to  the  por- 
tions which  are  best  suited  for  such  purposes. 

It  would  seem  that  the  following  locations  are 
especially  adapted  as  being  suited  for  the  perpetual 
maintenance  of  forests  on  them, — namely : 

1.  Wetlands. 


REFORESTATION  AND   TREE-PLANTING.      159 

2.  Lands  covered  with  thin  soil. 

3.  Lands  covered  with  a  rather  poor  soil. 

4.  Along  the  margins  of  all   rivers,  wherever 
the  land  is  not  actually  required  for  purposes  of 
roads  or  other  public  uses. 

5.  On  the  sides  of  all  mountain-slopes,  where 
the  soil  is  of  the  proper  character. 

6.  On  the  slopes  of  all  mountains   subject  to 
avalanches. 

The  following  translation  of  the  French  laws  of 
1860  for  reforestation  is  taken  from  the  report 
of  the  United  States  Commissioners  for  1877,* 
page  338 : 

FRENCH  CODE  OF  BEBOISEMENT  OF  MOUNTAINS,  JULY 
28,  1860. 

"ARTICLE  1.  Subventions  may  be  allowed  to  communes 
and  public  bodies,  or  to  individuals,  for  replanting  lands  on 
the  tops  or  slopes  of  mountains, 

"  ARTICLE  2.  These  aids  may  consist  either  in  the  delivery 
of  seeds,  or  plants,  or  in  premiums  in  money.  In  those  given 
by  reason  of  the  work  done  for  the  general  good,  and  in  cases 
of  communes  and  public  bodies,  regard  is  to  be  had  to  their 
resources,  and  the  sacrifices  they  must  make,  and  to  their  need, 
as  also  to  the  sums  given  by  general  councils  for  reboisement. 

*  Reprinted,  by  permission,  from  a  "  Report  upon  Forestry," 
1876,  by  Franklin  B.  Hough.  Washington:  Government 
Printing-Office,  1878.  Pp.  649. 


160  OUTLINES  OF  FORESTRY. 

"  ARTICLE  3.  Premiums  in  money  given  to  individuals  can- 
not be  paid  until  after  the  work  is  done. 

ARTICLE  4.  In  cases  where  the  public  interests  demand  that 
the  works  of  reboisement  should  be  made  obligatory,  either 
on  account  of  the  condition  of  the  soil,  or  the  dangers  that 
may  happen  to  the  lands  below,  proceedings  are  to  be  had 
as  follows : 

"  ARTICLE  5.  An  imperial  decree,  issued  in  council  of  state, 
declares  the  public  utility  of  the  works,  fixes  the  boundaries 
of  land  in  which  it  is  necessary  to  execute  the  reforesting, 
and  the  time  within  which  it  must  be  done.  This  decree  is 
preceded  (1)  by  an  open  inquiry  in  each  of  the  communes 
interested ;  (2)  by  a  deliberation  in  the  municipal  councils  of 
these  communes,  in  conjunction  with  those  most  important ; 
(3)  the  advice  of  a  special  commission,  composed  of  the  pre- 
fect of  the  department  or  his  delegate,  a  member  of  the  gen- 
eral council,  a  member  of  the  council  of  arrondissement,  an 
engineer  of  bridges  and  roads  or  of  mines,  a  forest-agent,  and 
two  landholders  of  the  commune  interested ;  (4)  the  advice  of 
the  council  of  arrondissement,  and  that  of  the  general  council. 

"  The  proems-verbal  specify  ing  the  lands,  the  plan  of  the  places, 
and  the  project  of  the  works  prepared  by  the  forest  adminis- 
tration, with  the  concurrence  of  an  engineer  of  bridges,  roads, 
or  of  mines,  are  to  be  deposited  in  the  office  of  the  mayor 
during  the  inquiry,  the  duration  of  which  is  one  month,  be- 
ginning with  the  publication  of  the  prefectoral  order,  which 
prescribes  the  opening  of  the  inquest  and  the  meeting  of  the 
municipal  council. 

"ARTICLE  6.  The  imperial  decree  is  to  be  published  and 
posted  up  in  the  communes  interested.  The  prefect  is  also  to 


REFORESTATION  AND   TREE-PLANTING.      161 

notify  the  communes  and  public  bodies,  as  well  as  individuals, 
by  an  extract  of  the  imperial  decree,  concerning  the  indications 
relating  to  the  lands  belonging  to  them.  The  act  of  notification 
shall  show  the  limit  of  time  allowed  for  the  work  of  reboise- 
ment,  and  if  there  is  occasion,  the  offer  of  aid  from  the  admin- 
istration on  the  advances  it  is  disposed  to  make. 

"  ARTICLE  7.  If  the  lands  included  within  the  limits  fixed 
by  the  imperial  decree  belong  to  individuals,  the  latter  are  to 
declare  whether  they  will  undertake  to  do  the  replanting 
themselves ;  and,  if  so,  they  are  to  be  held  to  execute  the 
work  within  the  time  fixed  by  the  decree.  In  case  they 
refuse  or  fail  to  perform  agreement,  proceedings  may  be  had 
for  their  expropriation,  on  the  ground  of  public  utility,  ob- 
serving the  formalities  prescribed  under  Title  II.  and  fol- 
lowing, of  the  law  of  May  3,  1841.  The  proprietor  expro- 
priated in  the  execution  of  this  article  has  the  right  to  re- 
gain possession  of  his  property  after  reboisement,  subject  to 
payment  of  charges  for  expropriation,  the  cost  of  labors  in 
principal  and  interest.  He  may  relieve  himself  of  the  price 
of  the  labors  by  relinquishing  half  of  the  property.  If  the 
proprietor  wishes  to  obtain  repossession,  he  should  make  a 
declaration  to  the  sub-prefect  within  five  years  after  notice  that 
the  work  of  reboisement  has  been  finished,  under  penalty  of 
forfeiture  of  this  right. 

"  ARTICLE  8.  If  the  communes  or  public  bodies  refuse  to 
execute  these  labors  upon  their  lands,  or  if  they  are  unable  to 
do  it,  the  state  may  acquire,  either  amicably  obtaining  a  part 
of  the  lands  which  they  will  not  or  cannot  replant,  or  by 
assuming  sole  charge  of  the  work.  In  the  latter  case,  it  will 
retain  the  care  and  use  of  the  lands  until  it  is  reimbursed  its 
I  14* 


162  OUTLINES  OF  FORESTRY. 

advances,  in  principal  and  interest.  Nevertheless,  the  com- 
mune shall  enjoy  the  right  to  pasturage  on  the  lands  replanted 
as  soon  as  it  is  found  beyond  risk  of  injury. 

"  ARTICLE  9.  Communes  and  public  bodies  may  in  all  cases 
exonerate  themselves  from  repayment  to  the  state,  by  relin- 
quishing one-half  of  the  replanted  lands.  This  abandonment 
should  be  made  under  loss  of  right  of  doing  so,  within  ten 
years  from  notice  of  the  completion  of  the  works. 

"  ARTICLE  10.  The  sowing  or  planting  cannot  be  made  on 
more  than  a  twentieth  in  one  year  of  the  surface  to  be  planted, 
unless  a  resolution  of  the  municipal  councils  authorizes  it  to 
be  done  to  a  greater  extent. 

"  ARTICLE  11.  Forest-guards  of  the  state  may  be  appointed 
for  the  care  of  the  sowing  or  planting  done  within  the  bounda- 
ries fixed  by  imperial  decrees.  Injuries  proved  by  these  guards, 
within  the  extent  of  these  limits,  shall  be  prosecuted  in  the 
same  manner  as  if  done  in  woods  subject  to  forest  regulation. 
The  execution  of  the  sentence  is  to  be  in  accordance  with  arti- 
cles 209,  211,  and  212,  and  paragraphs  1  and  2  of  article  210 
of  the  Forest  Code. 

"ARTICLE  12.  Paragraph  1  of  article  224  of  the  Forest 
Code  is  not  applicable  to  reboisement  done  with  aid  or  pre- 
miums from  the  state,  in  execution  of  the  present  law.  The 
owners  of  lands  replanted  with  aid  or  premiums  of  the  state 
may  not  pasture  their  cattle  without  special  license  from  the 
forest  administration,  until  the  time  when  such  woods  shall  be 
recognized  by  said  administration  as  sufficiently  protected. 

"  ARTICLE  13.  A  regulation  of  the  public  administration 
shall  determine  (1)  the  measures  to  be  taken  for  fixing  the 
boundaries  indicated  in  article  5  of  the  present  law ;  (2)  the 


REFORESTATION  AND   TREE-PLANTING.      163 

rules  to  be  observed  in  preservation  of  works  of  reboisement ; 
(3)  the  mode  of  determining  the  advances  made  by  the  state, 
and  the  measures  proper  for  assuring  repayment  of  principal 
and  interest,  and  the  rules  to  be  followed  in  the  relinquish- 
ment  of  lands  which  article  9  allows  communes  to  make  to 
the  state. 

"  ARTICLE  14.  The  sum  of  ten  million  francs  is  appropri- 
ated for  paying  the  expenses  authorized  by  the  present  law, 
to  the  extent  of  one  million  a  year.  The  minister  of  finances 
is  authorized  to  sell,  with  right  of  clearing,  if  necessary,  woods 
belonging  to  the  state,  to  the  value  of  five  million  francs. 

"  These  woods  may  only  be  taken  from  such  as  are  entered 
in  Table  B,  appended  to  this  law.  The  sales  shall  be  done  in 
succession,  within  ten  years  from  January  1,  1861.  The  min- 
ister of  finances  is  likewise  authorized  to  sell  to  communes, 
upon  approved  valuation,  and  on  conditions  fixed  by  a  rule  of 
the  public  administration,  the  woods  hereinabove  mentioned. 
The  five  million  francs  needed  to  complete  the  expenses  au- 
thorized by  the  present  law  shall  be  provided  by  means  of 
extraordinary  cuttings,  and,  if  necessary,  from  the  ordinary 
resources  of  the  budget." 


164  OUTLINES  OF  FORESTRY. 


XVII.  THE  BALANCE  OF  NATURE. 


such  a  complex  organization  as  the  earth  to 
be  properly  maintained  in  operation,  an  exact  bal- 
ance must  be  preserved  between  its  five  great 
geographical  forms  or  parts,  —  namely,  the  land, 
the  water,  the  air,  plants,  and  animals.  So  inti- 
mately are  these  different  parts  associated  with  one 
another,  and  so  exact  is  the  balance  that  is  main- 
tained between  them,  that  no  one  can  be  changed, 
either  in  amount  or  distribution,  without  markedly 
affecting  all  the  others. 

The  five  geographical  forms  receive  practically, 
entirely  from  the  sun,  all  the  energy  by  which 
they  are  actuated,  and  which  activity  constitutes 
the  order  of  created  things. 

A  part  of  the  heat  of  the  sun  stirs  the  air  or 
water  into  vast  movements  called  currents  that 
flow  between  the  equator  and  the  poles.  By  their 
means  an  interchange  is  effected  between  the  ex- 
cessive heat  of  the  equatorial  regions  and  the 
excessive  cold  of  the  poles.  Another  part  heats 


THE  BALANCE  OF  NATURE.  165 

the  earth's  surface,  and  causes  vapor  to  pass  off 
from  the  water  surfaces  into  the  atmosphere. 

Another  part  of  the  solar  energy  or  heat  is 
directly  expended  in  maintaining  one  or  another 
of  the  myriad  forms  of  plant  and  animal  life. 

If  any  of  the  five  great  geographical  forms  ap- 
propriates more  than  its  share  of  the  solar  energy, 
a  disturbance  of  the  balance  of  nature  is  effected, 
which  may  produce  far-reaching  changes  in  the 
operation  of  the  entire  mechanism. 

Let  us  inquire  as  to  some  of  the  more  evident 
ways  in  which  this  balance  of  nature  is  preserved, 
how  it  may  be  disturbed,  and  some  of  the  effects 
produced  by  such  disturbances. 

We  will  discuss  this  influence  from  the  stand- 
point of  the  five  great  geographical  forms, — 
namely,  the  land,  the  water,  the  air,  plants,  and 
animals. 

The  Land  and  Water. — An  exact  balance,  both 
in  the  amount  and  distribution,  of  the  land  and 
water  areas  of  the  earth  is  absolutely  necessary  for 
the  existence  of  the  earth's  present  plant  and  ani- 
mal life. 

The  total  water  areas  of  the  earth  are  in  excess 
of  the  land  areas  in  about  the  proportion  of  2J- 
tol. 


166  OUTLINES  OF  FORESTRY. 

The  most  extended  water  areas  are  situated  in 
the  equatorial  regions,  the  greater  part  of  the  land 
areas  being  situated  either  in  the  temperate  or  in 
the  polar  zones. 

At  the  equator,  therefore,  where  the  sun's  heat 
is  greatest,  there  exists  the  greatest  expanse  of 
water.  Here  are  three  readily-movable  elements, 
the  air,  the  water,  and  vapor,  each  of  which  can 
take  in  considerable  heat  without  growing  very 
hot.  The  differences  between  the  temperature  of 
the  equatorial  and  polar  regions  produce  vast  cur- 
rents, both  in  the  atmosphere  and  in  the  ocean, 
which  effect  an  interchange  between  the  excessive 
heat  at  the  equator  and  excessive  cold  at  the  poles. 

Even  a  comparatively  small  change  in  the  dis- 
tribution of  the  land  and  water  areas  of  the  earth 
would  produce  marked  changes  in  its  life. 

If,  for  example,  most  of  the  earth's  surface  in 
the  equatorial  regions  was  composed  of  land,  an 
excessive  temperature  would  be  thereby  produced 
that  would  render  the  equatorial  regions  abso- 
lutely uninhabitable  by  any  of  the  present  races  of 
man.  Consider,  for  example,  tropical  Africa.  The 
equator  by  no  means  crosses  this  continent  at  its 
greatest  breadth,  and  yet,  notwithstanding  the  fact 
that  nearly  all  the  continent  is  considerably  more 


THE  BALANCE  OF  NATURE.  167 

than  one  thousand  feet  above  the  sea  level,  large 
parts  of  its  interior  are  as  yet  absolutely  unknown 
to  the  white  man. 

What,  then,  would  be  the  effect  on  the  earth's 
present  life  if,  instead  of  the  present  excess  of 
water  surface  at  the  equator,  there  existed  an  ex- 
cess of  land  surface  ?  Beyond  doubt  the  present 
life  of  the  earth  would  be  swept  out  of  existence. 

In  the  same  manner  any  marked  increase  in 
either  the  elevation  or  the  extent  of  the  land  in 
the  polar  regions  would  be  followed  by  such  an  in- 
crease in  the  severity  of  the  cold  as  to  sweep  out 
of  existence  much  of  the  present  life  of  the  earth. 
It  was,  in  the  opinion  of  most  geologists,  a  change 
in  the  elevation  of  the  polar  lands  that  caused  the 
severe  cold  of  the  glacial  epoch,  when  most  of  the 
northern  continents  were  covered  with  enormous 
ice-fields. 

The  Air. — Any  change  in  the  composition  of  the 
earth's  atmosphere,  such,  for  example,  as  in  the 
amount  of  its  oxygen  or  its  carbonic  acid  gas, 
would  be  followed  by  a  change  in  its  animal  and 
plant  life. 

The  existence  of  animal  life  tends  to  decrease 
the  amount  of  oxygen  in  the  atmosphere,  and  to 
increase  the  amount  of  carbonic  acid.  The  ex- 


168  OUTLINES  OF  FORESTRY. 

istence  of  plant  life  tends  to  increase  the  amount 
of  oxygen  and  to  decrease  the  amount  of  carbonic 
acid  gas. 

A  wonderful  balance  is  maintained  in  nature  as 
to  the  composition  of  the  atmosphere,  from  the 
fact  that  what  plants  reject,  animals  require  for 
their  existence,  and  what  the  animals  reject,  plants 
require. 

Minerals,  Plants,  and  Animals. — The  mutual  in- 
terdependence of  the  mineral,  the  plant,  and  the 
animal  affords  another  illustration  of  the  balance 
of  nature.  Animals  obtain  their  food  either  from 
other  animals  or  from  plants.  Plants,  as  a  rule, 
live  on  minerals.  They  are  so  constituted  as  to  be 
able  to  take  the  various  substances  directly  from 
the  soil,  and  to  change  them  into  forms  that  can 
be  readily  assimilated  by  animals.  The  continued 
existence  of  animals  depends  on  the  continued 
existence  of  plants. 

Mature  has  very  carefully  insured  the  presence  of 
those  germs  or  seeds  that  are  absolutely  necessary 
for  the  birth  of  either  animals  or  plants.  To  in- 
sure the  presence  of  the  germs  in  all  cases,  the 
number  of  such  germs  produced  is  always  vastly 
in  excess  of  the  number  that  can  possibly  live.  In 
the  case  of  nearly  all  plants  and  animals  the  num- 


THE  BALANCE  OF  NATURE.  169 

ber  of  germs  produced  by  a  single  individual  is  so 
great,  that  if  they  all  lived  and  reproduced  their 
kind  at  the  same  rate,  in  a  very  little  while  the 
earth  itself  would  be  too  small  to  hold  them. 

Leuwenhoek  has  calculated  that  a  single  speci- 
men of  the  domestic  fly  can  produce  seven  hun- 
dred and  forty-six  thousand  four  hundred  and 
ninety-six  young  in  three  months. 

According  to  Professor  Owen,  a  single  aphis,  or 
plant  louse,  in  the  tenth  generation  produces  one 
quintillion  young. 

It  has  been  calculated  that  if  all  the  offspring 
of  a  single  edible  oyster  survived  for  but  a  com- 
paratively few  generations,  the  waters  of  such 
shallow  inlets  of  the  ocean  as  the  Chesapeake  Bay 
would  be  too  small  to  hold  them. 

In  order  to  avoid  this  excessive  multiplication  of 
the  animal  and  plant  life  of  the  earth, — and  the 
above  are  but  a  few  of  the  numerous  similar  cases 
that  might  be  quoted, — and  thus  preserve  the  bal- 
ance of  nature,  which  would  be  disturbed  by  such 
inordinate  multiplication  of  any  one  species,  all 
forms  of  animate  creation  have  their  natural  enemies 
provided  by  nature  to  hold  them  in  check.  Those 
only  continue  to  exist  that  are  best  fitted  to  exist 
under  the  conditions  by  which  they  are  surrounded. 

H  16 


170  OUTLINES  OF  FORESTRY. 

The  principle  of  the  survival  of  the  fittest  plays  an 
important  part  in  preserving  the  balance  of  nature. 

Nearly  every  animal  forms  the  food  best  fitted 
to  sustain  the  life  of  some  other  animal.  In  the 
event  of  a  too  rapid  multiplication  of  any  particu- 
lar form  of  life,  some  scourge  or  disease  appears 
which  sweeps  off  the  surplus  and  thus  restores 
nature's  balance. 

As  far  as  careful  measurements  have  been  made, 
it  can  be  safely  assumed  that  the  total  value  of  the 
solar  radiation  is  practically  the  same  now  as  it 
was  many  thousands  of  years  ago.  Consequently, 
the  total  amount  of  energy  which  the  earth  thus 
receives  from  the  sun,  and  which  goes  to  maintain 
the  present  mechanism  of  nature,  is  constant. 

The  distribution  of  this  solar  energy  is,  however, 
by  no  means  constant.  The  general  interchange 
that  is  effected  between  the  excessive  heat  of  the 
equator  and  the  excessive  cold  of  the  polar  regions 
may  take  place  rapidly  or  slowly,  and  thus  produce 
differences  in  the  earth's  general  climate  that  not 
infrequently  give  rise  to  a  belief  in  a  change  in 
the  total  heating  power  of  the  sun,  when  no  such 
change  exists.  For  example  : 

A  bare,  uncovered  surface  heats  with  extreme 
rapidity,  and  consequently  the  air  over  it  becomes 


THE  BALANCE  OF  NATURE.  171 

intensely  heated.  This  may  give  rise  to  an  im- 
pression that  the  sun's  heating  power  has  in- 
creased. 

Certain  causes  may  tend  to  temporarily  prevent 
the  free  interchange  of  heat  energy  that  usually 
exists  between  hot  and  cold  parts  of  the  earth. 
There  will  thus  result  an  increase  of  temperature 
in  one  locality  and  a  marked  deficit  in  another, 
which  would  thus  give  rise  to  the  impression  that 
variations  in  the  solar  radiation  existed,  when,  in 
reality,  such  variations  existed. 

In  the  case  of  the  evaporation  of  water  effected 
by  the  sun,  if  the  total  value  of  the  sun's  heat  be 
constant  it  might  at  first  sight  be  supposed  that 
the  total  quantity  of  evaporation  must  remain  con- 
stant, and  that,  therefore,  the  total  quantity  of 
heat  remaining  the  same,  no  change  in  its  distri- 
bution could  effect  a  change  in  the  amount  of  the 
evaporation,  and,  consequently,  in  the  value  of  the 
rainfall.  It  must  be  remembered,  however,  in  this 
connection,  that  if  circumstances  existed  in  the 
air  of  any  locality  by  which  during  the  time  of 
greatest  heat  the  moisture  was  retained  in  the  air 
of  such  locality,  and  not  be  removed  therefrom, 
evaporation  would  necessarily  be  much  smaller 
than  if  such  moisture  were  removed  by  any  cause. 


172  OUTLINES  OF  FORESTRY. 

The  total  quantity  of  the  evaporation,  therefore, 
would  by  no  means  be  constant. 

It  is  possible,  therefore,  that  while  the  existence 
of  the  forest  over  extended  sections  of  country 
tends  on  the  whole  rather  to  vary  the  distribution 
of  the  rainfall  through  a  change  in  the  rapidity  of 
the  drainage,  that,  nevertheless,  it  may  also,  to 
some  extent,  tend  to  produce  a  change  in  the  total 
quantity  of  the  rainfall. 

The  exact  balance  of  nature  that  is  required  to 
be  maintained,  in  order  that  the  present  life  of  the 
earth  shall  exist,  can  be  disturbed  by  many  means. 
In  perhaps  no  other  way  does  man  tend  more  to 
disturb  this  balance  than  by  the  destruction  of  the 
forests.  The  removal  of  the  forests  from  over  ex- 
tended areas  effects  a  disturbance  of  the  balance 
of  nature  that  is  manifested  in  the  following 
ways: 

1.  By  a  marked  change  in  the  heat  in  summer 
and  the  cold  of  winter  in  the   regions   formerly 
covered  by  forests. 

2.  By  a  marked  change  in  the  average  amount 
of  moisture  present  in  the  atmosphere  over  such 
regions. 

3.  By  a  marked  change  in  the  character  of  the 
soil  in  such  region. 


THE  BALANCE  OF  NATURE.  173 

4.  By  a  marked  change  in  the  drainage  of  such 
region. 

5.  By  a  marked  change  in  the  number  and  se- 
verity of  floods  and  droughts  in  such  regions. 

6.  By  a  marked  change  in  the  salubrity  of  the 
regions  through  which  the  rivers  flow  which  rise 
in  such  districts. 

7.  By  a  marked   change  in  the   number  and 
severity  of  hail-storms  in  such  regions. 

8.  By  an  increase  in  the  damage  to  the  agricul- 
tural districts  arising  from  the  appearance  of  early 
frosts  in  or  near  such  regions. 

The  preservation  of  the  forests,  in  at  least  certain 
localities,  is,  therefore,  imperatively  demanded  in 
order  to  maintain  the  general  balance  of  nature, 
and  to  insure  on  the  earth  a  place  for  the  com- 
fortable habitation  of  man. 

George  P.  Marsh,  in  his  work  entitled  "  The 
Earth  as  Modified  by  Human  Action/'  *  says  on 
page  8  : 

"  The  revolutions  of  the  seasons,  with  their  alternations  of 
temperature  and  of  length  of  day  and  night,  the  climates  of 
different  zones,  and  the  general  conditions  and  movements  of 

*  Reprinted,  by  permission,  from  "  The  Earth  as  Modified 
by  Human  Action,"  by  George  P.  Marsh.  New  York :  Scrib- 
ner,  Armstrong  &  Co.,  No.  654  Broadway,  1874.  Pp.  656. 

16* 


174  OUTLINES  OF  FORESTRY. 

the  atmosphere  and  the  seas,  depend  upon  causes  for  the  most 
part  cosmical,  and,  of  course,  wholly  beyond  our  control. 
The  elevation,  configuration,  and  composition  of  the  great 
masses  of  terrestrial  surface,  and  the  relative  extent  and 
distribution  of  land  and  water,  are  determined  by  geological 
influences  equally  remote  from  our  jurisdiction.  It  would 
hence  seem  that  the  physical  adaptation  of  different  portions 
of  the  earth  to  the  use  and  enjoyment  of  man  is  a  matter  so 
strictly  belonging  to  mightier  than  human  powers,  that  we 
can  only  accept  geographical  nature  as  we  find  her,  and  be 
content  with  such  soils  and  such  skies  as  she  spontaneously 
offers. 

"  But  it  is  certain  that  man  has  reacted  upon  organized  and 
inorganic  nature,  and  thereby  modified,  if  not  determined,  the 
material  structure  of  his  earthly  home.  The  measure  of  that, 
reaction  manifestly  constitutes  a  very  important  element  in 
the  appreciation  of  the  relations  between  mind  and  matter,  as 
well  as  in  the  discussion  of  many  purely  physical  problems. 
But,  though  the  subject  has  been  incidentally  touched  upon 
by  many  geographers,  and  treated  with  much  fulness  of  detail 
in  regard  to  certain  limited  fields  of  human  effort  and  to 
certain  specific  effects  of  human  action,  it  has  not,  as  a  whole, 
so  far  as  I  know,  been  made  a  matter  of  special  observation, 
or  of  historical  research,  by  any  scientific  inquirer.  Indeed, 
until  the  influence  of  geographical  conditions  upon  human 
life  was  recognized  as  a  distinct  branch  of  philosophical 
investigation,  there  was  no  motive  for  the  pursuit  of  such 
speculations ;  and  it  was  desirable  to  inquire  how  far  we  have, 
or  can,  become  the  architects  of  our  own  abiding-place,  only 
when  it  was  known  by  the  mode  of  our  physical,  moral,  and 


THE  BALANCE  OF  NATURE.  175 

intellectual  being  is  affected  by  the  character  of  the  home 
which  Providence  has  appointed,  and  we  have  fashioned,  for 
our  material  habitation. 

*•#•#••*#•*## 

"  We  cannot  always  distinguish  between  the  results  of  man's 
action  and  the  effects  of  purely  geological  or  cosmical  causes. 
The  destruction  of  the  forests,  the  drainage  of  lakes  and 
marshes,  and  the  operations  of  rural  husbandry  and  industrial 
art  have  unquestionably  tended  to  produce  great  changes  in 
the  hygrometric,  thermometric,  electric,  and  chemical  condi- 
tion of  the  atmosphere,  though  we  are  not  yet  able  to  measure 
the  force  of  the  different  elements  of  disturbance,  or  to  say 
how  far  they  have  been  neutralized  by  each  other,  or  by  still 
obscurer  influences  ;  and  it  is  equally  certain  that  the  myriad 
forms  of  animal  and  vegetable  life  which  covered  the  earth 
when  man  first  entered  upon  the  theatre  of  a  nature  whose 
harmonies  he  was  destined  to  derange  have  been,  through  his 
interference,  greatly  changed  in  numerical  proportion,  some- 
times much  modified  in  form  and  product,  and  sometimes 
entirely  extirpated. 

"  The  physical  revolutions  thus  wrought  by  man  have  not, 
indeed,  all  been  destructive  to  human  interests,  and  the 
heaviest  blows  he  has  inflicted  upon  nature  have  not  been 
wholly  without  their  compensations.  Soils  to  which  no  nutri- 
tious vegetable  was  indigenous ;  countries  which  once  brought 
forth  but  the  fewest  products  suited  for  the  sustenance  and 
comfort  of  man — while  the  severity  of  their  climates  created 
and  stimulated  the  greatest  numbers  and  the  most  imperious 
urgency  of  physical  wants — surfaces  the  most  rugged  and 
intractable,  and  least  blessed  with  natural  facilities  of  com- 


176  OUTLINES  OF  FORESTRY. 

munication,  have  been  brought  in  modern  times  to  yield  and 
distribute  all  that  supplies  the  material  necessities,  all  that 
contributes  to  the  sensuous  enjoyments  and  conveniences,  of 
civilized  life.  The  Scythia,  the  Thule,  the  Britain,  the 
Germany,  and  the  Gaul  which  the  Koman  writers  describe  in 
such  forbidding  terms  have  been  brought  almost  to  rival  the 
native  luxuriance  and  easily- won  plenty  of  Southern  Italy; 
and,  while  the  fountains  of  oil  and  wine  that  refreshed  old 
Greece  and  Syria  and  Northern  Africa  have  almost  ceased  to 
flow,  and  the  soils  of  those  fair  lands  are  turned  to  thirsty  and 
inhospitable  deserts,  the  hyperborean  regions  of  Europe  have 
learned  to  conquer,  or  rather  compensate,  the  rigors  of  climate, 
and  have  attained  to  a  material  wealth  and  variety  of  product 
that,  with  all  their  natural  advantages,  the  granaries  of  the 
ancient  world  can  hardly  be  said  to  have  enjoyed." 


PRIMER  OF  PRIMERS.  177 


XVIII.     PRIMER   OF   PRIMERS. 

FORESTRY  treats  of  the  care  and  preservation  of 
parts  of  the  earth  covered  by  trees,  together  with 
the  best  means  of  replanting  such  areas  when 
deprived  of  their  trees. 

When  the  germs  are  present,  trees  will  grow 
naturally  wherever  suitable  conditions  of  soil,  heat, 
and  moisture  exist. 

The  climatic  conditions  best  suited  for  the 
growth  of  trees  are  also  best  suited  for  the  growth 
of  men.  As  density  of  population  increases,  the 
trees  must  be  removed  from  large  areas : 

1.  For  agricultural  purposes. 

2.  For  the  location  of  roads. 

3.  For  the  wood  or  other  products. 

The  principal  product  of  the  forest  is  wood, 
which  is  required  for  fuel  or  charcoal,  for  building 
purposes  generally,  for  fences,  for  telegraph-poles, 
for  mining  purposes,  for  railroad  ties,  or  for  bark 
for  tanning. 

The  object  of  forestry  is  to  regulate  the  removal 
of  the  forest  where  necessary,  and  to  point  out  the 


178  OUTLINES  OF  FORESTRY. 

best  manner  in  which  the  products  of  the  forest 
may  be  harvested. 

Forestry  does  not  endeavor  to  preserve  intact 
the  virgin  forests  of  the  earth.  On  the  contrary, 
it  teaches  man  how  best  to  harvest  the  crops  of 
wood,  or,  where  necessary,  to  safely  effect  the 
entire  removal  of  the  forests. 

Among  the  different  kinds  of  areas  in  agricul- 
tural districts  suitable  for  tree-planting  are, — 

1.  Areas  covered  with  poor  or  thin  soils,  where 
other  crops  will  not  thrive. 

2.  "Wet  places,  where  other  crops  will  not  thrive. 

3.  On  the  borders  of  rivers  or  streams  generally. 

4.  On  mountain-slopes,  hill-tops,  or  other  eleva- 
tions. 

Forests  should  be  maintained  on  mountain- 
slopes,  because, — 

1.  The  rainfall  is  greatest  on  such  slopes. 

2.  Because  the  rivers  are  born  in  the  mountains, 
and,  when  the  forests  are  removed,  the  waters  drain 
so  rapidly  from   the   surfaces  of  the   slopes   that 
dangerous  floods  occur,  and  much  of  the  soil  is 
rapidly  carried  away. 

3.  Because  the  presence  of  the  forest  prevents 
the  occurrence  of  disastrous  droughts. 

4.  Because  the  presence  of  the  forest  prevents 


PRIMER  OF  PRIMERS.  179 

sudden  changes  in  the  temperature  of  the  air,  and 
thus  tends  to  increase  the  number  and  severity  of 
hail-storms. 

5.  Because  the  presence  of  the  forest  tends  to 
prevent    the   occurrence   of    early   frosts    in    the 
neighboring  agricultural  districts. 

6.  Because  the  presence  of  the  forest  insures  a 
greater    uniformity  in  the    relative   quantity   of 
moisture  in  the  air  at  different  seasons  of  the  year. 

All  life,  whether  animal  or  plant,  has  its  begin- 
nings in  a  minute  germ-cell  containing  a  nucleus 
surrounded  by  a  transparent  substance  called  pro- 
toplasm. 

Although  cases  exist  where  plants  appear  with- 
out the  apparent  sowing  of  seed,  yet,  in  all  such 
cases,  seeds  or  germs  must  have  been  present. 

The  conditions  necessary  for  plant-growth,  named 
in  the  order  of  their  importance,  are : 

1.  The  germ  or  seed. 

2.  The  sunshine  and  the  heatshine. 

3.  The  nourishment,  or  the  food  the  plant  re- 
quires for  its  growth. 

4.  The  cradle,  or  the  soil  in  which  the  plant  is 
born. 

When  a  particular  species  of  plant  life  is  to  be 
maintained,  the  character  of  the  soil  is  of  the 


180  OUTLINES  OF  FORESTRY. 

greatest  importance.  But  if  the  other  conditions 
of  heat,  light,  and  nourishment  exist,  almost  any 
soil  will  be  found  that  will  be  the  best  fitted  for 
some  few  of  the  great  variety  of  plants. 

The  germ  or  seed  is  in  all  cases  derived  from  a 
plant  similar  to  that  which  is  produced  when  such 
seed  grows  and  bears  fruit. 

The  soil  forms  the  plant's  cradle ;  in  it  the  plant 
spreads  its  roots,  and  obtains  the  water  and  min- 
eral ingredients  required  for  growth. 

The  moisture  and  carbonic  acid  taken  from  the 
air  by  a  plant  during  its  active  growth  form  the 
principal  part  of  the  plant's  structure;  the  various 
mineral  matters  taken  from  the  soil  form  but  a 
comparatively  small  part  of  such  structure. 

During  active  growth  in  the  presence  of  sun- 
shine, plants  take  in  or  absorb  carbonic  acid  from 
the  air.  Under  the  influence  of  sunlight,  this  car- 
bonic acid,  together  with  its  associated  water,  is 
eventually  decomposed,  the  carbon  and  hydrogen 
being  retained,  and  the  oxygen  thrown  off  into  the 
air. 

The  mineral  matters  in  the  soil  must  exist  in 
such  conditions  as  will  permit  of  ready  assimi- 
lation. 

Every  section  of  country  possesses  a  nationality 


PRIMER   OF  PRIMERS.  181 

in  its  plant  growth,  or  produces  a  particular  vari- 
ety of  plants  called  its  flora. 

The  differences  in  the  distribution  of  light,  heat, 
and  moisture  in  different  parts  of  the  earth  cause 
corresponding  differences  in  the  flora  of  such  parts. 

The  flora  of  the  equatorial  regions  consists  of 
such  plants  as  are  hest  fitted  to  exist  under  the 
conditions  of  abundant  heat,  light,  and  moisture 
of  these  regions. 

In  passing  from  the  equator  to  the  poles  the 
differences  in  the  distribution  of  heat  and  moist- 
ure cause  corresponding  differences  in  the  variety 
and  luxuriance  of  plant  life. 

In  passing  from  the  base  to  the  summit  of  a 
high  tropical  mountain  similar  differences  in  the 
variety  and  luxuriance  of  plant  life  are  noticed,  as 
in  going  from  the  equator  to  the  poles. 

Seed-time  and  harvest  seldom  fail  in  nature, 
because  the  germs  of  vegetable  life  are  generously 
scattered  in  all  regions  of  the  earth. 

The  agencies  provided  by  nature  for  widely 
scattering  the  seeds  of  plants  are  various.  Some 
seeds  are  provided  with  delicate  hair-like  wings, 
which  permit  the  wind  readily  to  carry  them  great 
distances  from  the  plants  which  produced  them. 
Others  are  provided  with  hooks  or  bristles,  which 

16 


182  OUTLINES  OF  FORESTRY. 

catch  in  the  fur  of  animals  or  in  the  plumage  of 
birds,  and  in  this  manner  are  often  carried  to 
distant  regions. 

Some  seeds,  which  are  swallowed  whole  by 
birds  or  other  animals,  often  pass  out  uninjured 
by  the  process  of  digestion  at  localities  far  distant 
from  where  they  were  produced. 

Civilized  man  either  purposely  or  accidentally 
carries  seeds  from  one  locality  to  another. 

It  sometimes  happens  that  plants  introduced 
into  a  particular  section  of  country  from  a  dis- 
tant land  find  the  new  soil  and  climate  so  favor- 
able to  growth  as  to  completely  drive  out  and 
exterminate  domestic  species. 

The  germs  or  seeds  of  plants  often  exhibit  a 
remarkable  tenacity  of  life  under  certain  circum- 
stances. Grains  of  corn  or  wheat  taken  from 
Egyptian  mummies  have  grown  and  borne  fruit, 
notwithstanding  their  centuries  of  rest. 

In  a  densely-wooded  section  of  country  the 
ground  is  often  so  thickly  covered  by  trees  as  to 
exclude  all  other  forms  of  vegetable  life.  When, 
however,  the  removal  of  a  few  trees  lets  in  the 
sunlight  and  heat,  the  seeds,  which  were  possibly 
slumbering  in  the  ground  for  centuries,  at  once 
spring  into  active  life. 


PRIMER  OF  PRIMERS.  183 

When  an  artesian  well  is  successfully  dug  in  the 
Sahara  Desert,  the  appearance  of  the  water  is 
almost  invariably  followed  by  the  appearance  of  a 
flora  that  often  contains  species  peculiar  to  such 
districts. 

Wherever  the  virgin  soil  of  the  prairies  is  up- 
turned, and  thus  exposed  to  the  air,  as  by  the 
wheels  of  the  settlers'  wagons  or  other  causes,  new 
species  of  plants  appear. 

In  the  North  Temperate  Zone  the  burning  of 
pine  forests  is  almost  invariably  followed  by  the 
appearance  of  scrub-oak. 

This  wide  distribution  of  plant  germs,  together 
with  their  wonderful  vitality,  insure  the  natural 
growth  of  a  vegetable  covering  in  all  regions  of 
the  earth  where  suitable  conditions  of  soil,  light, 
heat,  and  moisture  exist. 

The  character  of  the  vegetation  in  any  district 
depends  more  on  peculiarities  in  the  distribution 
of  light,  heat,  and  moisture  in  such  districts  than 
on  the  character  of  the  soil. 

The  peculiarities  in  the  distribution  of  the  rain- 
fall in  any  country  determine  to  a  great  extent  the 
character  of  the  flora  of  such  country. 

When  the  rainfall  in  any  region  is  entirely  ab- 
sent, no  matter  what  the  character  of  the  soil  may 


184  OUTLINES  OF  FORESTRY. 

be,  or  what  the  amount  of  light  and  heat  such  soil 
receives,  vegetation  will  be  entirely  absent,  and 
the  region  will  become  a  desert. 

Where  rain  falls  during  one  part  of  the  year, 
and  the  rest  of  the  year  is  dry,  steppe  regions 
occur.  Such  regions  are  covered  by  vegetation 
during  the  wet  season,  but  resemble  deserts  during 
the  dry  season. 

Meadows  and  prairies  occur  where  the  rainfall 
is  well  distributed  throughout  the  year,  and  the 
quantity  is  not  very  great. 

Forests  occur  where  there  is  an  abundant  rain- 
fall well  distributed  throughout  the  year. 

Forests  cannot  exist  in  any  part  of  the  North 
Temperate  Zone  where  the  rainfall  is  absent  for 
a  considerable  length  of  time,  because  the  trees 
would  die  during  the  dry  season,  and  there  would 
be  no  germs  for  a  new  crop  of  trees  to  start  grow- 
ing from  on  the  appearance  of  the  rainy  season. 

In  certain  parts  of  the  tropics  forests  may  exist 
despite  long  periods  of  drought,  because  in  such 
regions  the  growth  of  the  trees  is  either  considera- 
bly retarded,  or  the  trees  obtain  their  liquid  nour- 
ishment from  copious  dews  or  directly  from  the 
vapor  of  the  air. 

A  certain  depth  and  character  of  soil  are  neces- 


PRIMER  OF  PRIMERS.  185 

sary  for  the  growth  of  trees.  Such  a  soil  was 
formed  by  the  gradual  disintegration  of  hard 
rocks,  and  by  the  growth  and  subsequent  decay 
of  thousands  of  generations  of  plants. 

Forests  are  generally  found  on  the  slopes  of 
mountains,  where  the  rainfall  is  considerable  and 
well  distributed  throughout  the  year.  The  moun- 
tains are,  therefore,  the  natural  home  of  the  forest. 

Forests  are  found  especially  on  that  coast  of  an 
island  or  continent  which  is  exposed  to  the  preva- 
lent wind,  because  there  the  rainfall  is  considera- 
ble and  no  extended  time  occurs  when  the  rain  is 
absent. 

Soil  was  originally  formed  by  the  gradual  disin- 
tegration of  the  crystalline  rocks  that  were  pro- 
duced by  the  cooling  of  the  earth's  crust. 

Disintegration  of  rocks  is  effected  by  various 
causes,  mainly,  however,  by  the  action,  in  some 
way  or  another,  of  water. 

Sometimes  the  soil  is  found  resting  on  the  sur- 
face of  the  rock  from  which  it  was  derived  by 
disintegration.  In  such  cases  its  general  charac- 
ter can  be  directly  traced  to  the  composition  of  the 
underlying  rocks  by  the  gradual  change  which  can 
be  observed  from  the  loose,  porous  soil  on  top,  to 
the  hard,  untouched,  virgin  rock  below. 

16* 


186  OUTLINES  OF  FORESTRY. 

Soils  maybe  divided  into  gravelly,  sandy,  clayey, 
calcareous,  and  peaty. 

The  agencies  by  which  the  hard  crystalline 
rocks  may  be  broken  up  or  disintegrated  to  form 
soil  are, — 

1.  The  expansion  produced  during  the  sprout- 
ing or  growing  of  vegetation. 

2.  The   alternate    contractions    and   expansions 
that  attend  the  freezing  or  thawing  of  the  water 
that  sinks  into  the  rocks. 

3.  The  cutting  or  eroding  power  of  running- 
water  charged  with  suspended  mineral  matters. 

4.  The  eroding  or  cutting  power  of  glaciers. 

5.  The  solvent  power  of  water  containing  such 
gases  as  oxygen  or  carbonic  acid. 

A  plant,  during  its  vigorous  growth,  by  the  ex- 
pansion of  its  roots,  may  break  or  rend  a  rock, 
and  thus  aid  in  its  disintegration. 

The  alternate  expansions  and  contractions  that 
attend  the  thawing  or  freezing  of  the  water  which 
sinks  into  a  rock  gradually  break  the  rock  into 
fragments,  and  thus  aids  in  the  formation  of  soil. 

During  the  gradual  movements  of  glaciers  down 
the  mountain  valleys,  the  fragments  of  hard  rocks 
lodged  in  the  ice  cut  or  grind  the  rocks  which 
form  the  sides  of  the  valleys  through  which  the 


PRIMER  OF  PRIMERS.  187 

glaciers  move,  and  thus  aid  in  the  formation  of 
soil. 

When  water  contains  dissolved  in  it  oxygen  or 
carbonic  acid  gas,  it  may  gradually  dissolve  some 
of  the  less  insoluble  ingredients  of  the  hardest 
rocks,  and  thus  cause  them  to  become  permeable. 

Clayey  soils  are  derived  from  the  disintegration 
of  feldspathic  rocks. 

Calcareous  soils  are  derived  from  the  disintegra- 
tion of  limestones. 

Some  soils  possess  the  valuable  property  of  ab- 
sorbing moisture  directly  from  the  vapor  in  the 
air.  Soils  containing  a  large  quantity  of  vegetable 
humus  possess  this  property  in  a  more  marked 
degree  than  any  others.  Clayey  soils  also  possess 
it  to  a  marked  extent. 

The  ability  of  soils  to  absorb  the  sun's  heat  will 
vary  with  their  color.  Dark-colored  soils  absorb 
the  heat  much  better  than  light-colored  soils. 

The  plants  that  are  found  growing  naturally  in 
any  locality  are  those  which  are  best  fitted  to  grow 
in  such  locality.  They  will  continue  to  grow 
naturally  only  so  long  as  these  favorable  con- 
ditions are  maintained. 

Forests  require  for  their  continued  existence  a 
certain  character  of  soil,  so  that,  although  even  all 


188  OUTLINES  OF  FORESTRY. 

the  climatic  conditions  requisite  for  their  growth 
exist,  they  cannot  appear  until  such  soil  is  provided. 

Like  other  forms  of  creation,  the  forest  is  forced 
to  maintain  a  continual  struggle  for  existence. 

Its  enemies  may  be  divided  into  two  classes, — 
namely,  animate  and  inanimate. 

The  principal  animate  enemies  of  the  forest  are 
plants,  animals,  and  man. 

The  principal  inanimate  enemies  of  the  forest 
are  fire,  winds,  floods,  and  avalanches. 

The  destruction  of  the  forest  by  fire  is  generally 
complete.  Though  in  some  cases  a  small  fire  may, 
by  destroying  the  less  hardy  forms  of  plant  life, 
increase  the  growth  of  certain  trees,  such,  for 
example,  as  the  pitch-pine,  yet,  in  general,  exten- 
sive forest  fires  generally  so  completely  remove  the 
forests,  that  it  is  often  impossible  to  re-establish 
them. 

Severe  forest  fires  generally  occur  during  the 
dry  season  of  the  year.  The  rain  which  subse- 
quently falls  finds  the  ground  unprotected  by  any 
vegetable  covering,  and,  rapidly  draining  off  the 
surface,  carries  away  much  soil. 

The  principal  causes  of  forest  fires  are  the  camp- 
fire,  the  burning  of  brush,  the  locomotive  spark, 
the  lightning-bolt,  and  at  times,  perhaps,  the  heat- 


PRIMER  OF  PRIMERS.  189 

ing  power  of  the  sun's  rays  concentrated  by  len- 
ticular, resinous,  or  gummy  nodules. 

"When  its  velocity  is  great,  the  wind  sometimes 
sweeps  away  the  trees  from  extended  areas.  This 
action  of  the  wind  is  limited  mainly  to  the  edges 
of  the  forest  or  to  openings  made  in  them  by  any 
cause. 

By  overflowing  their  banks,  rivers  sometimes 
undermine  and  carry  away  thousands  of  acres  of 
forest  trees.  The  trees  accumulate  in  the  bed 
of  rivers  and  form  masses  called  rafts. 

An  avalanche  sweeping  down  the  slope  of  a 
mountain  often  completely  removes  the  forest.  A 
plot  of  forest  land,  properly  placed,  will  often 
check  the  movements  of  avalanches. 

The  animate  enemies  of  the  forest  often  produce 
their  greatest  destruction  by  the  aid  of  the  inani- 
mate enemies.  Thus,  man  destroys  forests  by  fire ; 
the  beaver,  by  floods. 

Various  parasitic  plants  may  grow  on,  and 
thus  cause  the  death  of,  even  the  most  vigorous 
trees. 

Some  forms  of  fungus-growth  cause  considera- 
ble damage  to  the  trees  on  which  they  grow. 

The  animal  enemies  of  the  forest  vary  in  size 
from  minute  insects  to  animals  of  large  size. 


190  OUTLINES  OF  FORESTRY. 

The  ravages  of  the  animal  kingdom  are  most 
marked  on  the  borders  of  the  forest.  In  the 
deeper  recesses,  the  vegetable  kingdom  holds 
almost  undisputed  sway,  excluding  the  animal 
forms  by  the  density  of  its  growth. 

Domestic  animals,  when  allowed  to  range  freely 
through  the  forest,  may  cause  considerable  damage, 
by  destroying  the  foliage,  or  by  gnawing  the  bark 
of  trees. 

Among  wild  animals,  rodents  are  the  most  de- 
structive by  gnawing  the  bark,  and  often  by  com- 
pletely girdling  the  trees. 

Rabbits,  mice,  and  beavers  are  among  the  ro- 
dents that  cause  the  greatest  damage  to  the 
forests. 

Beavers  destroy  forests  not  only  by  actually 
cutting  down  trees,  but  also  by  building  dams 
which  cause  the  overflowing  of  the  adjacent  coun- 
try, which  thus  destroys  the  timber  growing 
thereon. 

Goats  and  other  animals  that  live  largely  on  the 
bark  of  trees  often  work  great  destruction  to  the 
forests. 

Insects  cause  damage  to  the  forests,  either  by 
feeding  on  the  parts  of  the  tree  necessary  for  re- 
production or  growth,  or  by  making  galleries  or 


PRIMER  OF  PRIMERS.  191 

tunnellings  through  the  wood.  Many  insects, 
while  in  the  larva  state,  cause  great  damage  to 
trees  by  boring  or  eating  the  wood. 

Various  caterpillars  often  cause  so  great  a  de- 
struction to  the  pine-trees  as  to  completely  destroy 
extensive  pine  forests. 

The  greatest  enemy  of  the  forest  is  man.  As 
lord  of  the  forest  he  is  entitled  to  its  products,  and 
if  he  exercises  judgment  he  can  safely  harvest  his 
forest  crops. 

The  removal  of  the  forests  from  any  considera- 
ble section  of  country  is  almost  invariably  attended 
by  some  or  all  of  the  following  results, — namely : 

1.  An  increase  in  the  frequency  and  severity  of 
the  inundations  of  the  rivers  flowing  in  or  through 
such  districts. 

2.  An  increase  in  the  number  and  severity  of 
droughts  in  such  districts. 

3.  A  rapid  loss  of  the   soil  of  the   area  from 
which  the  trees  have  been  removed. 

4.  A  marked  disturbance  in  the  lower  courses 
of  the  rivers  which  rise  in,  or  flow  through,  such 
districts. 

5.  An  increase  in  the  number  and  severity  of 
hail-storms. 

When  the  forests  are  removed  from  any  area, 


192  OUTLINES  OF  FORESTRY. 

the  rain  which  falls  on  such  area,  instead  of 
slowly  draining  into  the  river  channel  during  a 
comparatively  long  time,  drains  rapidly  into  it 
and  causes  disastrous  floods.  The  reservoirs  of 
the  springs  in  such  districts  thus  failing  to  receive 
their  proper  supply  of  water,  are  apt  to  dry  up 
shortly  after  the  beginning  of  the  drought. 

The  rapid  drainage  of  the  areas  from  which  the 
forests  were  removed  causes  a  loss  of  its  surface- 
soil. 

The  soil  thus  lost  to  the  highlands  is  deposited 
in  the  lower  courses  of  the  rivers,  in  the  shape  of 
mud-flats,  or  sand-bars,  which  injuriously  affect 
navigation. 

"When  soil,  rich  in  vegetable  humus,  deposited 
on  the  lowlands  near  the  mouths  of  rivers,  is  ex- 
posed to  the  sun's  heat,  is  apt  to  cause  miasmatic 
or  other  diseases. 

The  ground  left  bare  by  the  destruction  of  the 
forest  permits  it  to  both  take  in  and  part  with  its 
heat  rapidly,  and  thus  to  permit  the  air  over  it 
to  rapidly  grow  hot  in  summer  and  cold  in  winter. 

Forests  should  be  maintained  in  some  parts  of 
all  regions  where  trees  can  grow.  The  best  places 
for  such  purposes  are  to  be  found  on  the  slopes  of 
mountains. 


PRIMER   OF  PRIMERS.  193 

From  every  water  surface  of  the  earth  vapor  is 
almost  constantly  passing  into  the  atmosphere. 
This  vapor  diffuses  through  the  air  over  such 
water  surfaces,  and  is  carried  hy  the  winds  to 
different  regions  of  the  earth. 

The  heat  which  turns  water  into  vapor  disap- 
pears, or  becomes  what  is  commonly  called  latent 
heat.  When  such  vapor  is  sufficiently  chilled  and 
falls  as  rain,  snow,  or  other  form  of  precipitation, 
the  latent  heat  becomes  sensible  and  warms  the 
surrounding  air. 

The  rapidity  with  which  water  evaporates  or 
passes  into  the  air  as  vapor  varies  with  the  follow- 
ing circumstances : 

1.  The  extent  of  the  surface  exposed. 

2.  The  temperature  of  the  air. 

3.  The  quantity  of  vapor  already  in  the  air. 

4.  The  pressure. 

The  vapor  which  passes  into  the  air  exerts  a 
considerable  influence  in  moderating  the  extreme 
temperatures  that  would  otherwise  exist  in  the 
equatorial  and  polar  regions  of  the  earth,  in  the 
following  ways,  viz. : 

1.  By  effecting    an    interchange    between    the 
excessive  heat  of  the  equatorial  regions  and  the 
excessive  cold  of  the  polar  regions, 
i        n  17 


194  OUTLINES  OF  FORESTRY. 

2.  By  acting  as  a  screen  which  both  prevents  the 
earth's  surface  from  being  too  rapidly  heated  on 
exposure  to  the  sun's  rays,  or  too  rapidly  cooled 
when  deprived  of  such  rays. 

Since  air  can  hold  more  vapor  when  hot  than 
when  cold,  if  the  temperature  of  a  mass  of  warm 
moist  air  is  sufficiently  cooled,  the  moisture  it  can 
no  longer  hold  as  vapor  appears  as  rain  or  as  some 
other  form  of  precipitation. 

The  lowering  of  temperature  required  to  pro- 
duce rain  is  obtained  : 

1.  By  warm  moist  air  blowing  along  the  earth's 
surface  towards  colder  regions. 

2.  By  warm  moist  air  rising  directly  from  the 
earth's  surface  into  the  higher  and  colder  regions 
of  the  atmosphere. 

Rain  is  generally  caused  by  warm  moist  air 
blowing  towards  the  polar  regions  of  the  earth. 
Cold  dry  air  blowing  towards  the  equatorial  re- 
gions has  its  capacity  for  moisture  increased,  and 
tends  rather  to  cause  droughts  than  rain. 

In  tropical  regions,  a  wind  that  has  crossed  an 
ocean,  and  has  thereby  become  saturated  with 
moisture,  may  bring  rain  on  reaching  the  coast  of 
a  continent  or  island,  in  no  matter  from  what 
direction  it  comes. 


PRIMER   OF  PRIMERS.  195 

More  rain  falls  in  the  equatorial  regions  than 
elsewhere ;  more  falls  in  the  temperate  than  in  the 
polar  regions.  More  rain  falls  on  the  coasts  of 
continents  than  in  the  interior. 

Where  the  temperature  is  sufficiently  high,  as  in 
the  equatorial  regions,  rain  may  be  caused  by  the 
chilling  produced  by  ascending  currents. 

Mountains  cause  a  heavy  rainfall  on  account  of 
the  air  being  chilled  when  forced  to  ascend  their 
cold  slopes. 

Nearly  all  the  great  rivers  of  the  world  rise  in 
mountainous  districts. 

The  rain  that  falls  on  the  earth  either  runs  di- 
rectly off  the  surface  or  sinks  slowly  into  the 
ground.  The  part  that  runs  directly  off  the  sur- 
face collects  in  streams  that  discharge  directly  into 
the  rivers.  The  part  that  sinks  into  the  ground 
collects  in  underground  basins,  from  which  it 
slowly  emerges  as  springs. 

When  the  mountains  are  covered  by  forests,  the 
rain  which  falls  on  their  slopes,  for  the  greater 
part,  drains  slowly  into  the  ground.  When  the 
mountains  are  denuded  of  their  forests  most  of 
the  rain  drains  rapidly  off  the  surface.  The  de- 
struction of  the  forests  on  mountain-slopes  is, 
therefore,  apt  to  cause  floods. 


196  OUTLINES  OF  FORESTRY. 

The  running  of  the  water  from  a  higher  to  a 
lower  level  is  called  drainage. 

There  are  two  kinds  of  drainage : 

1.  Surface  drainage,  where  the  water  runs  di- 
rectly off  the  surface  into  the  rivers. 

2.  Underground  drainage,  where  it  first  sinks 
into  the    ground    and   afterwards   discharges    as 
springs  into  the  rivers. 

Underground  drainage  takes  place  slowly.  Sur- 
face drainage  takes  place  rapidly. 

The  direction  in  which  rivers  flow  depends  on 
the  direction  in  which  the  land  slopes. 

The  main  stream,  with  all  its  tributaries  and 
branches,  is  called  the  river  system.  The  land 
which  drains  into  a  river  system  is  called  the  river 
basin.  The  size  of  the  river  depends  on  the  ratio 
between  the  quantity  of  the  rainfall  and  the  size 
of  the  river's  basin. 

"When  a  river  basin  is  covered  with  a  loose,  por- 
ous soil,  such  as  it  will  have  when  covered  with 
almost  any  form  of  vegetation,  the  rain  sinks 
slowly  into  the  earth  and  the  river  seldom  over- 
flows its  banks. 

When  the  area  is  such  that  most  of  the  water 
runs  directly  off  the  surface,  as  will  generally  be 
the  case  when  deprived  of  its  vegetable  covering, 


PRIMER  OF  PRIMERS.  197 

the  rivers  receiving  such  drainage  are  apt  to  over- 
flow their  banks  during  the  wet  season. 

Any  disturbance  in  the  natural  drainage  of  a 
country  may  cause  damage  from  the  too  rapid 
drainage  of  its  surface  : 

1.  By  insuring   too  much  water  in  its   rivers 
during  inundations. 

2.  By  insuring   too   little  water   in    its   rivers 
during  drought. 

The  preservation  of  forests  on  mountain-slopes, 
where  the  drainage  is  more  rapid  than  elsewhere, 
insures  a  proper  drainage  of  its  surface,  and  con- 
sequently the  proper  flow  of  its  rivers. 

The  condition  of  the  air  of  a  country  as  regards 
its  heat  or  cold  moisture  or  dryness,  healthfulness 
or  unhealthfulness,  is  called  its  climate. 

The  atmosphere  receives  its  heat  from  the  sun  : 

1.  Directly,  by  absorption. 

2.  Indirectly,  from  the  heated  earth. 

The  atmosphere  receives  its  heat  indirectly  from 
the  heated  earth : 

(a)  By  contact  with  the  heated  earth. 

(b)  By  radiation  from  the  heated  earth. 

(c)  By  reflection  from  the  heated  earth. 

All  parts  of  the  earth  in  the  same  latitude  do 
not  possess  the  same  temperature,  because  the 

17* 


198  OUTLINES  OF  FORESTRY. 

surface  is  higher  in  some  places  than  it  is  in 
others,  in  some  places  is  covered  with  vegetation 
and  in  others  is  bare,  or  is  exposed  to  cold  or 
currents  of  wind  or  water  in  some  places  and  to 
warm  currents  in  others. 

Differences  in  the  elevation  of  the  land  cause 
differences  in  the  temperature  of  the  air.  An 
elevation  of  three  hundred  and  fifty  feet  will  cause 
the  same  lowering  of  temperature  as  a  difference 
of  one  degree  of  latitude, — viz.,  of  1°  Fah. 

The  same  changes  of  temperature  are  observed 
in  passing  from  the  base  to  the  summit  of  a  high 
tropical  mountain  as  in  passing  along  the  earth's 
surface  from  the  equator  to  the  poles. 

Portions  of  the  earth's  surface  covered  by  water 
heat  or  cool  slowly;  consequently,  the  air  over 
such  portions  does  not  change  its  temperature 
rapidly,  or,  in  other  words,  such  portions  of  the 
earth  possess  an  equable  climate.  Portions  of 
the  earth  covered  by  land  heat  and  cool  rapidly ; 
consequently,  the  air  over  such  portions  changes 
its  temperature  rapidly,  or,  in  other  words,  such 
portions  possess  a  variable  climate. 

A  surface  covered  with  vegetation — such,  for 
example,  as  a  forest — does  not  change  its  tempera- 
ture as  rapidly  as  it  would  if  it  were  bare.  Forests, 


PRIMER   OF  PRIMERS.  199 

therefore,  tend  to  prevent  sudden  changes  in  the 
climate. 

A  bare,  uncovered  area,  such  as  a  desert,  is  sub- 
ject to  sudden  changes  in  its  climate. 

The  climate  produced  by  an  extended  land  area 
is  called  a  continental  climate;  that  produced  by 
an  extended  water  area,  an  oceanic  climate.  A 
continental  climate  is  characterized  by  great  and 
sudden  changes  of  temperature;  an  oceanic 
climate,  by  a  comparatively  uniform  temperature. 
The  forests  tend  to  produce  a  climate  characterized 
by  a  comparatively  uniform  temperature.  In  this 
respect,  therefore,  the  forest  climate  is  like  the 
oceanic  climate. 

The  sun  does  not  heat  an  area  covered  by  forests 
either  as  intensely  or  as  rapidly  as  a  bare  area, 
because : 

1.  The  heat  is  spread  over  the  greatly-extended 
surfaces  formed  by  the  trees  of  the  forest  and  its 
underbrush. 

2.  The  vegetable  covering  acts  as  a  screen  to 
protect  the  ground  from  the  direct  action  of  the 
sun's  rays. 

3.  The  air  over  the  forest  is  moister  than  that 
over  the  fields,  and  this  moist  air  acts  either  as  a 
screen  to  protect  it  from  the  heat  of  the  sun, 


200  OUTLINES  OF  FORESTRY. 

or  to  prevent  the  loss  of  its  own  heat  by  radia- 
tion. 

Therefore,  an  area  of  ground  covered  with  for- 
ests is  subjected  to  smaller  changes  of  temperature 
than  a  bare,  uncovered  area. 

The  climate  of  the  forest  is  more  equable  than 
that  of  the  open  fields,  because  the  forest  takes 
in  and  parts  with  its  heat  more  slowly  than  the 
fields. 

A  layer  of  snow  tends  to  preserve  the  tempera- 
ture of  the  ground  on  which  it  falls.  If  snow 
falls  on  unfrozen  ground,  the  ground  will  probably 
remain  unfrozen  throughout  the  year  until  the 
snow  melts ;  and,  when  the  melting  occurs,  the 
water  will  drain  slowly  into  the  earth.  If,  how- 
ever, the  snow  falls  after  the  ground  is  frozen,  the 
ground  will  probably  remain  frozen  until  the  snow 
melts,  when  the  water  will  drain  rapidly  off  the 
surface. 

The  presence  of  the  forest  tends  to  keep  the 
ground  unfrozen  until  protected  by  a  layer  of 
snow,  and  in  this  way,  when  the  snow  melts,  the 
water  sinks  quietly  into  the  ground,  and  disastrous 
floods  are  thus  avoided.  . 

The  forest,  by  keeping  the  air  over  it  moister  than 
that  over  the  fields,  increases  the  ability  of  the  air 


PRIMER  OF  PRIMERS.  201 

to  take  in  heat,  either  directly  from  the  sun,  or  in- 
directly from  the  heated  earth. 

Forests  prevent  sudden  changes  of  temperature 
throughout  the  year.  In  early  autumn  they  de- 
crease the  frequency  of  destructive  frosts  by  pre- 
venting the  temperature  of  the  air  from  rapidly 
falling. 

The  presence  of  forests  over  extended  areas  pre- 
vents the  occurrence  of  sudden  changes  of  tem- 
perature. 

1.  By  permitting  such  areas  to  more  thoroughly 
absorb  the  sun's  heat,  on  account  of  the  greater 
surfaces  they  possess. 

2.  By  keeping  the  air  over  the  forests  moister 
than  over  the  open  fields,  thus  enabling  it  more 
readily  to  absorb  the  sun's  heat. 

3.  By  acting  as  a  screen  to  the  lands  lying  to  the 
leeward  of  cold  winter  winds. 

4.  By  preventing  the   frosts   from   penetrating 
great  distances  into  the  ground,  and,  therefore,  in- 
creasing the  chance  of  winter  snows  falling  on 
unfrozen  ground. 

The  atmosphere  is  composed  of  a  mixture  of 
about  seventy-seven  per  cent,  by  weight  of  nitro- 
gen and  twenty-three  per  cent,  of  oxygen.  It  also 
contains  a  nearly  constant  quantity  of  carbonic 


202  OUTLINES  OF  FORESTRY. 

acid  gas  and  a  variable  quantity  of  the  vapor  of 
water. 

The  oxygen  of  the  air  is  necessary  for  animal 
life.  The  carbonic  acid  gas  is  necessary  for  plant 
life.  The  moisture  is  necessary  for  both  animal 
and  plant  life. 

Animals  take  in  oxygen  and  give  out  carbonic 
acid  gas.  During  growth,  when  exposed  to  sun- 
shine, plants  take  in  carbonic  acid  gas  and  give  out 
oxygen. 

The  presence  of  both  animal  and  plant  life, 
therefore,  is  necessary  to  keep  the  composition  of 
the  atmosphere  the  same. 

In  the  geological  past  the  earth's  atmosphere 
was  vaster  than  at  present.  It  contained  more 
oxygen  and  more  carbonic  acid  than  it  does  now. 
Much  of  the  oxygen,  which  then  existed  in  a  free 
state  in  the  air,  is  now  combined  with  various  ma- 
terials that  form  the  earth's  crust. 

The  excess  of  carbonic  acid  which  existed  in  the 
earth's  atmosphere  during  the  geological  past  was 
removed  from  it  mainly  by  the  plants  of  the  car- 
boniferous period,  and  now  exists  in  the  earth  as 
beds  of  coal. 

In  order  to  avoid  any  disturbance  in  the  balance 
between  plant  and  animal  life  of  the  earth,  forests, 


PRIMER   OF  PRIMERS.  203 

which  represent  the  largest  forms  of  plant  life, 
should  be  preserved. 

Hail  occurs  when  considerable  differences  of 
temperature  exist  between  neighboring  masses  of 
very  moist  air. 

The  destruction  of  the  forest,  by  readily  per- 
mitting such  differences  of  temperature  to  occur, 
tends  to  increase  the  number  and  severity  of  hail- 
storms. 

A  hail-storm  is  generally  preceded  by  the  ap- 
pearance of  several  layers  of  dark  grayish  clouds, 
and  a  violent  movement  is  often  seen  to  occur  be- 
tween them,  that  is  probably  of  a  whirling  char- 
acter. 

Hail-storms  are  almost  invariably  attended  by 
marked  disturbances  in  the  electrical  equilibrium 
of  the  atmosphere. 

A  hailstone  is  formed  of  alternate  layers  of  ice 
and  snow.  Various  explanations  have  been  offered 
to  account  for  the  peculiar  structure.  Volta  as- 
cribed it  to  the  alternate  attractions  and  repulsions 
occurring  between  neighboring  snow-  and  rain- 
clouds,  when  charged  with  opposite  kinds  of  elec- 
tricity. 

In  France,  where  Volta's  theories  were  formerly 
received,  lightning-rods  were  fruitlessly  erected  on 


204  OUTLINES  OF  FORESTRY. 

the  fields  in  order  to  protect  them  from  the  ravages 
of  the  hail. 

The  peculiar  structure  of  the  hailstone  has  also 
been  ascribed  to  a  whirling  motion  of  the  air  be- 
tween snow-  and  rain-clouds  around  a  horizontal 
axis,  whereby  particles  of  snow  are  carried  alter- 
nately into  the  rain-  and  snow-clouds,  and  thus 
receive  their  alternate  coatings. 

Another  theory  accounts  for  the  alternate  coat- 
ings of  ice  and  snow  by  the  exposure  of  moisture 
to  the  different  temperatures  occurring  in  denser 
and  rarer  portions  of  space  around  which  the  wind 
is  whirling. 

By  reforestation  is  meant  the  replanting  of  trees 
in  any  locality  from  which  they  have  been  removed 
either  accidentally  or  purposely. 

Provided  the  removal  of  the  forest  has  not  been 
attended  by  too  great  a  loss  of  soil,  the  same  kind 
of  trees  may  be  successfully  replanted. 

There  are  two  methods  by  means  of  which 
reforestation  may  be  effected. 

1.  Sowing  or  Seeding. 

2.  Tree  Planting. 

Seeding  can  be  profitably  followed  in  the  tem- 
perate latitudes  where  the  growth  of  the  tree  is 
comparatively  certain.  In  higher  latitudes  the 


PRIMER   OF  PRIMERS.  205 

planting  of  the  tree  is,  perhaps,  preferable,  since 
the  germination  and  continued  growth  of  seeds 
are  by  no  means  certain. 

Where  the  destruction  of  the  forest  has  been 
caused  by  an  avalanche,  the  removal  of  the  soil, 
in  some  cases,  is  so  complete  that  trees  cannot  be 
successfully  replanted. 

In  some  of  the  western  parts  of  the  United 
States  it  is  now  recognized,  from  actual  experience, 
that  when  trees  are  planted  in  plots  around  the 
farm-lands,  the  protection  thus  afforded  the  rest 
of  the  farm-land,  against  the  winds,  is  of  greater 
money-value  than  the  rent  of  the  ground  occupied 
by  such  trees. 

The  following  locations  are  especially  adapted  to 
tree  planting : 

1.  "Wetlands. 

2.  Lands  covered  with  a  thin  or  poor  soil. 

3.  Along  the  margins  of  rivers  where  the  land 
is   not  required   for   roads   or   other  public  pur- 
poses. 

4.  On  the  side  of  mountain-slopes  where  the  soil 
is  of  the  proper  character,  or  subject  to  destructive 
avalanches. 

An  exact  balance  must  be  preserved  between 
the  five  great  geographical  forms, — namely,  the 

18 


206  OUTLINES  OF  FORESTRY. 

land,  the  water,  the  air,  the  plants  and  animals,  in 
order  that  the  complex  organization  of  nature  may 
be  properly  maintained  in  operation. 

The  energy  which  is  the  cause  of  nearly  all 
natural  phenomena  of  the  earth  is  received  directly 
from  the  sun. 

One  part  of  the  sun's  heat  stirs  the  air  and 
water  in  vast  movements  between  the  equator  and 
the  poles,  and  thus  effects  an  interchange  between 
the  too  great  heat  of  the  equatorial  regions  and 
the  too  feeble  heat  of  the  polar  regions.  Another 
part  of  the  solar  energy  is  directly  expended  in 
producing  one  or  another  of  the  myriad  forms  of 
plant  or  animal  life. 

If  the  land,  the  water,  or  the  air  receives  more 
than  its  share  of  solar  energy,  a  disturbance  in 
the  balance  of  nature  is  effected,  which  produces 
marked  effects  in  the  life  of  the  earth. 

The  total  water  area  of  the  earth  bears  a  pro- 
portion to  its  total  land  area  very  nearly  as  25  is  to 
9,  or  as  2£  is  to  1. 

The  earth  receives  its  greatest  heat  from  the 
sun  at  those  parts  of  its  surface  where  it  has  its 
greatest  water  areas,  only  a  comparatively  small 
part  of  the  land  being  found  in  the  equatorial  re- 
gions. There  are  produced,  however,  vast  currents 


PRIMER  OF  PRIMERS.  207 

in  the  atmosphere  and  in  the  ocean,  which  effect 
an  interchange  between  the  heat  of  the  equator 
and  the  cold  of  the  poles. 

Any  change  in  the  distribution  of  the  land  and 
water  areas  of  the  earth,  either  as  regards  their 
relative  amount,  or  as  regards  their  distribution, 
would  seriously  affect  the  life  of  the  earth. 

If  the  greatest  proportion  of  land  existed  at  the 
equator,  such  changes  would  be  produced  in  the 
earth's  climate  as  to  sweep  its  present  life  out  of 
existence. 

Any  change  in  the  elevation  of  the  present  land 
areas  would  produce  a  marked  change  in  the 
earth's  climate.  It  was  probably  an  increase  in 
the  elevation  of  the  polar  lands  that  caused  the 
severe  cold  of  the  glacial  epoch,  when  so  much 
of  the  northern  continents  were  covered  with 
ice. 

In  order  to  preserve  the  present  relative  propor- 
tions of  oxygen  and  carbonic  acid  in  the  atmos- 
phere, the  present  animal  and  plant  life  of  the 
earth  must  be  preserved. 

Animals  are  absolutely  dependent  on  plants  for 
their  existence.  The  plants  can  take  their  food 
directly  from  the  air  and  the  soil.  Animals  re- 
quire their  food  to  be  prepared  for  them  by  the 


208  OUTLINES  OF  FORESTRY. 

plants  on  which  they  live.  The  death  of  the  plant 
life  of  the  earth  would,  therefore,  be  followed  by 
the  death  of  all  its  animals. 

Many  animals  multiply  so  rapidly  that,  unless 
they  were  removed  from  the  earth  by  furnishing 
food  for  other  animals,  a  marked  disturbance  would 
be  effected  in  the  balance  of  nature. 


APPENDIX. 


LISTS  OF  TKEES  SUITABLE  FOE  REPLANTING  IN 
DIFFERENT  PORTIONS  OF  THE  UNITED  STATES. 

IN  order  to  extend  the  scope  of  the  OUTLINES  OF  FOR- 
ESTRY, and  to  render  it  of  greater  practical  value,  the  follow- 
ing circular  letter  was  sent  to  different  well-known  authorities 
in  forestry,  inquiring  as  to  lists  of  trees  suitable  for  replanting 
in  different  sections  of  the  United  States. 

Circular  Letter. 


PHILADELPHIA,  January  23, 1892. 

1809  Spring  Garden  Street. 


PROF.  ,. 


DEAR  SIR, — I  am  about  publishing  a  little  work  on  For- 
estry, and  am  desirous  of  obtaining  a  list  of  trees  suitable  for 

planting  for  reforestation  in  such  parts  of. 

and  the  adjoining  States  as  have  been  denuded  of  forests, 
or  are  capable  of  sustaining  forest  trees. 

In  the  event  of  your  being  able  to  spare  the  time  necessary 
o  18*  209 


210  APPENDIX. 

to  send  me  a  list  of  such  trees,  I  would,  of  course,  make  full 
acknowledgment  in  the  book  of  your  contribution. 

If  your  time  is  too  fully  occupied  to  send  me  the  infor- 
mation requested,  can  you  inform  me  where  I  can  obtain  the 
same? 

Asking  your  pardon  for  thus  trespassing  on  your  valuable 

time,  I  am, 

Very  respectfully,  yours, 

EDWIN  J.  HOUSTON. 

The  letters  received  in  reply  to  the  foregoing,  together  with 
the  lists  of  trees  suitable  for  purposes  of  reforestation,  are 
hereunto  appended. 

From  Thomas  Meehan,  Editor  of  Meehan's  Monthly,  German- 
town,  Philadelphia. 

MEEHAN'S  MONTHLY, 
GERMANTOWN,  PHILADA.,  January  30, 1892. 

PROP.  EDWIN  J.  HOUSTON, 

1809  Spring  Garden  Street,  Philadelphia. 
DEAR  SIB, — I  have  marked  in  the  catalogue  sent  to-day 
the  names  of  such  trees  as  are  most  desirable  for  planting  on 
the  Northeastern  Seaboard  of  the  United  States.  A  few  are 
rare,  but  will  soon  become  common ;  others  are  not  likely  to 
become  common  for  some  years.  In  some  cases  the  trees 
marked  would  have  but  limited  usefulness,  but  all  are  of 
value  in  some  respect  or  another. 

When  getting  into  the  States  along  the  seaboard  of  the 
Virginia  line,  many  of  those  named  would  be  ineligible. 
Very  truly  yours, 

THOMAS  MEEHAN. 


APPENDIX.  211 

DECIDUOUS   TREES. 

MAPLES. 

Acer  campestre,  or  European  Cork  Maple. 
"    palatanoides,  or  Norway  Maple. 
"    pseudo-platanus,  or  European  Sycamore  Maple. 

HORSE-CHESTNUT. 

jEsculus  glabra,  or  American  Horse-Chestnut. 

"       hippocastanum,  or  European  Horse-Chestnut. 

AILANTUS. 

Ailantus  glandulosa. 

BIRCH. 

Betula  alba,  or  European  White  Birch. 

HICKORY. 

Carya  alba,  or  Shell-bark  Hickory. 
"      amara,  or  Bitternut  Hickory. 
"      microcarpa,  or  Small-Fruited  Hickory. 
"      sulcata,  or  Large-Fruited  Hickory. 
"      tomentosa,  or  White  Hickory. 

SWEET  CHESTNUT. 

Castanea  Americana,  or  American  Chestnut. 

HOLLY. 

Hex  opaca,  or  American  Holly. 

JUNIPER,  CEDARS. 

Juniperus  Virginiana,  or  Eed  Cedar. 

FIR. 

Picea  balsamea,  or  Balsam  Fir. 

PINE. 

Pinus  Austriaca,  or  Australian  Pine. 
"      Banksiana. 
"      densiflora,  or  Japan  Pine. 
"     Laricio,  or  Corsican  Pine. 


212  APPENDIX. 

Pinus  Massoniana. 
"     pungens. 

"  resinosa,  or  Eed  Pine. 
"  rigida,  or  Pitch  Pine. 
"  miiis,  or  Yellow  Pine. 
"  strobus,  or  White  Pine. 

JAPAN  CYPRESS. 

Retinispora  obtusa. 

ARBOR-VIT\flS. 

Thuja  oceidentalis,  or  American  Arbor  Vitse. 

LOCUST,  ACACIA. 

JRobinia  pseudacacia,  or  Yellow  Locust. 

MAIDEN-HAIR  TREE.     GINGKO. 

/Salisb&ria  adiantifolia. 

WILLOW. 

Salix  alba,  or  White  Willow. 

"    Babylonica,  or  Weeping  Willow. 

"   japonica,  or  Japan  Willow. 

"    pentandra,  or  Laurel-leaved  Willow. 

"    Russettiana. 

"    wtellina,  or  Golden-Bark  Willow. 

ELMS. 

Ulmus  Americana,  American  Elm. 
"      campestris,  or  English  Elm. 
"     fulva,  or  Slippery  Elm. 
"     racemosa,  or  American  Cork  Elm. 

EVERGREENS. 
SPRUCE. 

Abies  alba,  or  White  Spruce. 
"     Canadensis,  or  Hemlock. 


APPENDIX.  213 


Abies  Douglasii,  or  Douglas  Spruce. 

"     excelsa,  or  Norway  Spruce. 

"    pungens,  or  Colorado  Blue  Spruce. 
LARCH. 

Larix  Europcea,  or  European  Larch. 

SWEET  GUM. 

lAquidambar  styraeiflua. 

SOPHORA. 

Sophora  Japonica. 

DECIDUOUS  CYPRESS. 

Taxodium  distichum. 

LINDEN. 

Tilia  Americana,  or  American  Linden. 
"    Europcea,  or  European  Linden. 

POPLAR. 

Populus  alba,  or  Silver  Poplar. 

"       balsamifera,  or  Balsam  Poplar. 
"      fastigiata,  or  Lombardy  Poplar. 


"  monilifera,  or  Carolina  Poplar. 
OAK. 

Quereus  alba,  or  White  Oak. 

"  bicolor,  or  Swamp  White  Oak. 

"  cerris,  or  Turkey  Oak. 

"  coccinea,  or  Scarlet  Oak. 

"  dentata  (Daimio),  or  Japan  Oak. 

"  falcata,  or  Spanish  Oak. 

"  imbricaria,  or  Laurel  Oak. 

"  macrocarpa,  or  Mossy  Cup. 

"  nigra,  or  Black  Jack  Oak. 

"  obtusiloba,  or  Post  Oak. 


214  APPENDIX. 

Quereus  palustriis,  or  Pin  Oak. 
"      phellos,  or  Willow  Oak. 
"      prinus,  or  Eock  Chestnut  Oak. 
"       robur,  or  English  Oak. 
"       rubra,  or  Eed  Oak. 
"       tinctoria,  or  Black  Oak. 

MULBERRY. 

Mortis  alba,  or  White  Mulberry. 

"     rubra,  or  American  Eed  Mulberry. 
BOX  ELDER. 

Negundofraxinotfolium,  or  Ash-leaved  Maple. 
SOUR  GUM. 

Nyssa  multiflora. 

IRONWOOD. 

Ostrya  Virginica. 

EMPRESS-TREE. 

Paulownia  imperialis. 

BUCKEYE. 

Pavlaflava,  or  Yellow  Buckeye. 

CHINESE  CORK-TREE. 

Phellodendron  amurense. 

PLANERA. 

Planera  cuspidata. 

BUTTONWOOD,  PLANE. 

Plantanus  ocddentalis,  or  American  Plane, 

orientalis,  or  Oriental  Plane. 
HONEY  LOCUST. 

Gleditschia  triacanthos,  or  Honey  Locust. 

KENTUCKY  COFFEE. 

Gymnocladus  Ganadensis. 


APPENDIX.  215 

HOVENIA. 

Hovenia  dulcis. 

IDESIA. 

Idesia  polycarpa. 
WALNUT. 

Juglans  cinerea,  or  Butternut. 

"       regia,  or  English  Walnut,  or  Madeira  Nut, — south 

of  Philadelphia. 
TULIP-TREE. 

Liriodendron  tulipifera,  or  Common  Tulip-Tree,  or  Tulip 
Poplar. 

OSAGE  ORANGE. 

Madura  aurantiaca. 

MAGNOLIA. 

Magnolia  acuminata,  or  Cucumber-Tree. 
"        macrophylla. 
"        tripetala,  or  Umbrella-Tree. 

CATALPA. 

Catalpa  bignonioides,  or  Catalpa. 
"       speciosa,  or  Western  Catalpa. 

NETTLE-TREE. 

Celtis  occidental™,  or  Nettle-Tree. 

CHERRY. 

Cerasus  avium  alba  plena,  Double-flowering  Cherry. 
"      Pennsylvania,  or  Wild  Red- Cherry. 
"      ranunculceflora. 

DOGWOOD. 

Cornus  Florida,  or  White  or  Large-flowering  Dogwood. 

PERSIMMON. 

Diospyros  Virginiana,  or  American  Persimmon. 


216  APPENDIX. 

BEECH. 

Fagus  Americana,  or  American  Beech. 
"     sylvatica,  or  European  Beech. 

ASH. 

Fraxinus  Americana,  or  White  Ash. 
"        excelsior,  or  European  Ash. 
"        quadrangulata,  or  Blue  Ash. 
"        sambud/olia,  or  Black  Ash. 
"        viridis,  or  Green  Ash. 

KATSURA. 

Cercidiphyllum  japonicum. 


From  B.  S.  Hoxie,  Secretary  of  the  Wisconsin  State  Horticultural 
Society. 

WISCONSIN  STATE  HORTICULTURAL  SOCIETY, 

EVANSVILLE,  WISCONSIN,  January  26, 1892. 

EDWIN  J.  HOUSTON,  Philadelphia,  Pa. 

DEAR  SIR, — Yours  of  the  28th  at  hand.  I  mailed  to  your 
address  our  last  volume,  No.  2,  I  think.  The  list  of  trees 
found  on  page  9,  which  we  recommend  for  general  planting, 
will  be  found  applicable  to  nearly  all  parts  of  our  State. 

The  pine  regions  of  Wisconsin  are  the  parts  that  are  now 
being  deforested,  and  no  special  effort  is  being  made  to  re- 
forest these  areas.  Oak,  ash,  maple,  birch,  elm,  pine,  and 
spruce  will  grow  on  most  of  this  land. 

We  have  several  townships  bordering  on  Lake  Superior  in 
Bayfield  County,  which  some  ten  years  ago  were  set  apart 
as  a  State  Park.  Last  winter  a  bill  was  introduced  to  bring 
this  reservation  into  the  market, — i.e.,  to  sell  the  timber,  but  it 


APPENDIX.  217 

failed  to  pass,  and  if  my  pen  and  the  press  can  prevent  such 
a  bill,  it  will  never  pass.  If  I  can  be  of  any  further  assistance 
to  you,  please  write  me. 

I  shall  be  glad  to  see  your  book  when  published. 

EespectMly, 

B.  S.  HOXIE. 

TREES   AND   SHRUBS   RECOMMENDED. 

Trees  and  shrubs  recommended  in  the  "  Annual  Report  of 
the  Wisconsin  State  Horticultural  Society."  * 

EVERGREENS. 
For  general  planting  in  the  order  named : 

White  Pine. 

Norway  Spruce. 

White  Spruce. 

Arbor  Vitae. 

Balsam  Fir. 

Austrian  Pine. 

Scotch  Pine. 
For  ornamental  planting  in  the  order  named : 

Hemlock. 

Bed  Cedar. 

Siberian  Arbor  Vitse. 

Dwarf  Pine. 

Bed  or  Norway  Pine. 

*  Annual  Report  of  the  Wisconsin  State  Horticultural  Society,  em- 
bracing papers  read  and  discussions  thereon  at  the  semi-annual  meeting 
held  in  Black  River  Falls,  June  26,  27,  1890  j  also  at  Madison,  June 
2-6,  1891.  Vol.  xxi.  p.  9. 

K  19 


218  APPENDIX. 

DECIDUOUS  TREES. 
For  Timber. 
White  Ash. 
Black  Walnut. 
Hickory. 
Black  Cherry. 
Butternut. 
White  Oak. 
European  Larch. 
American  Larch. 

Street  Shade- Trees. 
White  Elm. 
Hard  Maple. 
Basswood  or  Linden. 
Ashleaf  Maple  (Acer  negundo.) 
Norway  Maple. 
Hackberry. 

For  Lawn  Planting. 

Weeping  Cut-leaved  Birch, 
American  Mountain  Ash. 
Green  Ash. 
Horse-Chestnut. 
European  Mountain  Ash. 
Wisconsin  Weeping  Willow. 
Oak-leaved  Mountain  Ash. 
White  Birch. 

Weeping  Golden-barked  Ash. 
Weeping  Mountain  Ash. 
Weeping  Poplar. 


APPENDIX.  219 

From   Charles  Mohr,  Agent  for  the  Forestry  Division  of  the 
United  States  Department  of  Agriculture,  Mobile,  Alabama. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

MOBILE,  ALABAMA,  January  31, 1892. 

PROF.  EDWIN  J.  HOUSTON,  Philadelphia,  Pa. 

DEAR  SIR, — Your  letter  of  the  23d  has  been  received. 
According  to  your  request,  I  send  you  enclosed  a  list  of  timber 
trees,  which  might  be  regarded  as  adapted  for  the  reforestation 
of  denuded  areas  in  the  Gulf  States  east  of  the  Mississippi 
Eiver. 

In  the  selection  of  the  trees,  I  had  to  be  guided  solely  by 
my  observations  made  in  the  different  sections  of  the  regions 
named,  and  had  to  confine  myself  entirely  to  native  species, 
no  information  being  on  hand  in  regard  to  trees  from  other 
sections  of  the  United  States,  or  exotics. 

To  shorten  matters,  I  refer  you  for  information  about  the 
habits  of  the  species  named  in  the  list,  to  the  preliminary  of 
important  forest  trees  in  the  United  States,  in  Mr.  Fernow's 
"  Eeport  to  the  Commissioners  of  Agriculture"  (Forestry  Di- 
vision) for  the  year  1886,  where,  also,  notes  on  the  economic 
uses  of  each  will  be  found.  The  numbers  in  my  list  refer  to 
the  same  species  mentioned  in  the  above  report. 
I  remain  truly  yours, 

CHARLES  MOHR. 

White  Cedar,  Chamcecyparis  sphwroidea. 
Red  Cedar,  Juniperus  Virginiana. 
Bald  Cypress,  Taxodium  distichum. 
Long-leaved  Pine,  Pinus  palustris. 
Loblolly  Pine,  Pinus  tceda. 


220  APPENDIX. 

Cuban  Pine,  Pinus  Cuberms. 

Short-leaved  Pine,  Pinus  mitis. 

White  Oak,  Quercus  alba. 

Cow  Oak,  "       Michauxii.    Kich,  alluvial  soil. 

Chestnut  Oak,    "       prinus. 

Live  Oak,  "       virens.    Lower  districts. 

Bed  Oak,  "       rubra. 

Black  Oak,        "       tinctoria.    Gravelly  uplands. 

Spanish  Oak,     "       falcata.    Throughout  on  lighter  soils. 

Water  Oak,        "       aquatica.    Of  value  for  fuel  only. 

Willow  Oak,  "  Phellos.  Rapid  growth  on  wet  or  dry 
light  soil.  Timber  more  valuable. 

Beech,  Fagus  ferruginea. 

Chestnut,  Costarica  vulgaris,  var.  American.  In  dry,  some- 
what silicious  soils  throughout. 

Shell-bark  Hickory,  Oarya  alba.    Upper  and  central  districts. 

Mocker  Nut,  Carya  tomentosa. 

Pecan,  Hickoria  Pecan  (Carya  olivceformis).  Valuable  for  its 
fruit. 

Wild  Cherry,  Prunus  serotina. 

Sweet  Gum,  Liquidambar  Styradflua. 

Black  Locust. 

Honey  Locust. 

Bed  Mulberry,  Morus  rubra.    Shade-loving. 

Magnolia,  Magnolia  grandifiora. 

Cucumber  Tree,  Magnolia  acuminata.  In  well-drained,  deep, 
and  lighter  loamy  soil,  through  the  State.  Shade-loving. 

Tulip-Tree,  Liriodendron  tulipifera. 

Osage  Orange,  Madura  aurantiaca. 

White  Ash,  Fraxinus  Americana.    Upper  district.   < 


APPENDIX.  221 

Green  Ash,  Fraxinus  viridis. 

Red  Maple,  Acer  rubrum. 

Silver  Maple,  "    dasycarpum. 

White  Elm,  UZmus  Americana.    Upper  district. 

Slippery  Elm,    "    fulva. 

Water  Elm,       "     alata,    Alluvial,  wet  soil. 

American  Linden,  Tilia  Americana,    Central  to  upper  district. 

Sycamore,  Plantanus  occidentalis. 

Cottonwood,  Populus  monilifera. 

From  JKobert  W.  Furnas,  Secretary  of  the  Nebraska  State  Board 
of  Agriculture. 

NEBRASKA  STATE  BOARD  OF  AGRICULTURE, 
^BROWNVILLE,  NEBRASKA,  January  27, 1892. 

EDWIN  J.  HOUSTON,  ESQ., 

1809  Spring  Garden  Street,  Philadelphia,  Pa. 

DEAR  SIR, — Keply  to  yours,  First,  twenty-third.  Of  the  more 
valuable  hard-wood  varieties  of  timber  used  for  forestry  pur- 
poses on  our  prairies,  or  naturally  timberless  region,  we  find 
the  best,— black  walnut,  white  ash,  black  and  honey  locust, 
black  cherry,  Kentucky  coffee-tree,  hard  maple,  burr  and 
white  oaks. 

Of  the  soft  woods, — soft  maple,  box  elder,  cottonwood,  and 
the  catalpas, — speciosa,  and  Tea's  hybrid. 

Evergreens :  red  cedar,  Scotch,  Australian,  and  white  pines. 
Both  American  and  European  larch  do  well. 
If  I  can  serve  the  forestry  cause  in  any  way,  command  me. 

Truly, 

ROBERT  W.  FURNAS. 
19* 


222  APPENDIX. 

From  Professor  M.  G.  Kern,  Editor  of  Coleman's  Rural  World. 

ST.  Louis,  January  26, 1892. 
EDWIN  J.  HOUSTON,  ESQ.,  Philadelphia,  Pa. 

DEAR  SIR, — Your  favor  of  the  twenty-third  inst.  received. 

Kindly  excuse  a  few  remarks  on  Western  forestry,  rather 
outside  of  the  list  of  available  trees  requested.  But  a  part  of 
Missouri  is  heavily  timbered,  and  in  these  sections  the  great 
object  of  the  population  is  to  get  rid  of  the  timber  for  money 
or  for  agricultural  purposes.  Many  portions  of  the  State  are 
cleared  to  the  same  extent  as  the  older  States,  with  abundance 
of  forest  supplies  for  present  use.  Part  of  the  State  is  prairie, 
in  which  the  need  of  timber  culture  is  as  great  as  in  all  open 
plains.  South  of  us  is  Arkansas,  a  mountainous  native  forest ; 
west,  Kansas,  Nebraska,  and  North  Iowa,  with  her  endless 
prairies.  A  wide  field,  indeed,  for  forest  management,  reforest- 
ing, and  timber  culture.  The  soil  brings  forth,  mostly  with 
rapid  growth,  all  the  indigenous  species  of  our  forests ;  a  list 
of  such  could  be  valuable  only  in  ratio  to  the  value  of  the 
timber  grown. 

Fast-growing  soft  woods  are  considered  in  wooded  sections 
as  of  little  value,  scarcely  worth  planting  on  a  large  scale. 
They  are  generally  planted  for  shelter,  ornament,  or  quick 
shade.  No  line  of  difference  as  to  hardiness  can  in  reality  be 
drawn,  though  variety  of  conditions  make  certain  kinds  more 
suitable  to  certain  localities:  we  differ  in  this  respect  from 
more  northern  latitudes. 

The  question  of  reforesting  denuded  sections  has  thus  far 
attracted  but  little  public  attention.  Intelligent  husbandry 
steadily  advancing,  is  gradually  awaking  to  the  necessity  of 
reforestation  and  the  protection  of  native  forests.  The  pros- 


APPENDIX.  223 

pective  value  of  economic  timber  is  realized  by  many,  and 
the  growth  of  young  native  timber  is  encouraged  by  the  usual 
means  of  protection  from  cattle  and  disastrous  fires. 

Systematic  forest  culture,  for  which  there  is  so  boundless  a 
field,  has  thus  far  been  practised  to  but  small  extent,  though 
every  intelligent  citizen  knows  that  the  most  valuable  kinds 
of  timber  are  being  exhausted  very  fast.  How  long  this  spell 
of  popular  indifference  will  last  cannot  be  foretold  by  the 
wisest.  Millions  of  acres  in  the  lowlands  and  on  hill-sides 
capable  of  producing  the  most  valuable  timbers,  lie  idle  as 
though  belonging  to  some  Indian  tribe. 

Much  popular  education  is  surely  needed  to  break  the  bar- 
riers of  indifference  and  popular  selfishness  underlying  all  the 
evil.  We  need  a  tow-line  attached  to  the  dormant  intelligence 
of  the  people  (as  far  as  American  forestry  is  concerned),  to 
draw  it  into  action.  When  once  aroused  from  the  dream  of 
inexhaustible  forest  wealth,  the  West  will  do  its  honest  share 
in  forest  culture,  as  her  resources  are  almost  without  limit. 

My  most  sincere  wishes  for  the  success  of  your  forthcoming 
work  on  Forestry.  Command  my  services  at  any  time  when 
special  features  of  information  from  this  section  are  desired. 

Very  respectfully, 

M.  G.  KERN. 

TREES  PRINCIPALLY  GROWN  IN  FOREST  CULT- 
URE  IN  MISSOURI  AND  ADJOINING  SECTIONS. 

Initial  Step  in  Forest  Culture. 
Cotton-wood. 
Black  Walnut. 
Soft  Maple. 


224  APPENDIX. 

Box  Elder. 

White  American  Ash. 

Sugar  Maple  (to  some  extent). 
Second  Step. 

The  introduction  of  Catalpa  species.  At  present  the 
above  with  Black  Walnut  and  White  Ash  are  the  leading  trees. 

Worthy  of  extensive  culture,  though  sparsely  planted  thus 
far,  are : 

Tulip-Tree  (Yellow  Poplar). 

The  leading  White  Oak  species. 

White  Oak. 

Over-cup  Oak. 

Burr  Oak. 

Post  Oak. 

White  Hickory  (under  certain  conditions). 

Of  Conifers. 

Bald  Cypress  (for  alluvial  lowlands). 

Eed  Cedar,  for  limestone  uplands  and  stony  slopes. 

White  Pine,  especially  suited  for  sandstone  formations 
found  in  sections  of  Southwestern  Missouri  and  Arkansas. 
Ornamental  trees  of  this  species,  met  everywhere,  show  re- 
markable vigor  of  growth  and  adaptation  to  the  formation. 

Black  Cherry  (to  be  recommended  for  general  culture). 

European  Alder,  for  moist  and  loamy  soils,  of  rapid 
growth,  and  valuable  wood.  One  of  the  best  of  temporary 
nursery  trees  for  larger  plantations. 

Soft  Woods. 
Soft  Maple. 
Box  Elder. 
Birch  (both  nigre  and  lenta). 


APPENDIX.  225 

Willows. 
Poplars. 

Plantanus,  Elms,  Sycamore,  for  various  purposes  of  shade, 
shelter,  and  wind-breaks. 

Evergreens. 

American  White  Spruce  deserves  far  more  attention  than 
thus  far  enjoyed.  It  is  the  most  lasting  of  all  spruces. 

Norway  Spruce. 

Scotch  and  Austrian  Pine  are  valuable  for  close  planta- 
tions for  shelter.  They  are,  however,  deficient  as  to  longevity, 
losing  their  vigor  much  sooner  than  the  native  American 
species. 

European  Larch  is  suited  to  the  northern  parts  of 
Missouri,  Iowa,  and  farther  north. 

UNIVERSITY  OP  PENNSYLVANIA, 
PHILADELPHIA,  PA.,  February  27, 1892.  \ 

PROF.  EDWIN  J.  HOUSTON, 

1809  Spring  Garden  Street,  Philadelphia,  Pa. 
MY  DEAR  PROFESSOR, — I  am  in  receipt  of  your  favor  of 

the  20th  inst.,  and  I  take  pleasure  in  sending  you  a  list  of 

trees  suitable  for  planting  in  the  Southwestern  States  and 

California. 

JBetula  occidentalis,  Hook.  Black  Birch.  For  ornamental  pur- 
poses, grows  ten  to  twenty  feet  high. 

Quercus  undulata,  Torr.  Oak.  Four  varieties,  valuable  for 
timber  and  for  masting,  furnishing,  as  they  do,  an  abun- 
dance of  sweet,  edible  acorns. 

Salix  cor  data,  Muhl.,  var.  vestita,  Anders,  Diamond  Willow, 
abundant  in  Yellowstone  regions,  valuable  for  furnishing 
unique  canes. 
P 


226  APPENDIX. 

Salix  purpurea,  L.  Purple  Willow,  six  to  fifteen  feet.  Best  of 
hedge  and  osier  willows.  Correspond  with  United  States 
Department  of  Agriculture  concerning. 

Salix  ludda,  Muhl.  Shining  Willow,  five  to  ten  feet.  One  of 
the  most  beautiful  willows  for  ornamental  planting. 

Salix  fragilis,  L.  Brittle  Willow,  Crack  Willow,  Bedford  Wil- 
low, sixty  to  eighty  feet,  affords  best  willow  timber,  and 
contains  large  per  cent,  of  tannin,  and  more  salicin  than 
others. 

Salix  alba,  L.,  vars.  Salix  cseruea  and  Salix  Vitellina,  Blue 
Willow,  and  Golden  Willow.  Particularly  useful  as  os- 
sier  or  basket-making  willows. 

Populus  nigra,  Black  Poplar,  thirty  to  forty  feet,  of  rapid 
growth,  wood  valuable  for  flooring,  cooperage,  and  for 
gunpowder  charcoal. 

Populus  tremuloides,  MX.  American  Aspen,  "  Quaking  Asp," 
twenty  to  fifty  feet. 

Populus  nigra,  var.  dilatata,  Lombardy  Poplar,  tall,  spire- 
shaped  tree,  of  rapid  growth,  to  be  set  in  rows  for  wind- 
breaks. 

Populus  monilifera,  Ait.  Necklace  Poplar,  large  tree,  one 
hundred  and  fifty  feet  high,  light,  soft  wood,  useful  for 
box  manufacture,  and  especially  for  paper  pulp. 

Juniperus  Virginiana,  L.  North  American  Red  Cedar,  or  Pencil 
Cedar.  The  largest  of  American  junipers,  sixty  to  ninety 
feet,  furnishes  a  light,  fragrant,  and  imperishable  wood. 

Abies  concolor,  Small  Balsam  Fir,  or  White  Fir,  eighty  to  one 
hundred  feet. 

Abies  nobilis, 

Abies  magnifica, 


'm>        \EedFir. 
gmfica,   J 


APPENDIX.  227 

Abies  religiosa,  the  Sacred  Fir  of  Mexico. 
"     bracteata,  one  hundred  feet. 
"     Chnadensis,  MX.    Common  Hemlock,  fifty  to  eighty  feet. 

Pseudoteuga  Douglasii,  Can.  Douglas  Spruce,  one  hundred 
and  fifty  to  three  hundred  feet. 

Picea  Engelmanni,  Eng.    Spruce,  sixty  to  one  hundred  feet. 
"    pungens,  Eng.  Balsam  Spruce,  sixty  to  one  hundred  feet. 

Pinus  flexilis,  James.    Pine,  sixty  feet. 

Pinus  ponderosa,  Dougl.  var.  Scrophulorum,  Eng.  Yellow 
Pine,  eighty  to  one  hundred  feet. 

Salisburia  adiantifolia  (or  Ginkgo  biloba),  forty  to  eighty  feet. 

Pinus  edulis,  Eng.    The  Pifion  or  Nut  Pine,  ten  to  fifteen  feet. 

Sequoya  semperviceus,  Sequoya  gigantea,  Ked  Wood,  two  hun- 
dred to  three  hundred  feet,  wood  almost  imperishable. 
Both  these  trees  should  be  planted,  as  they  are  likely  to 
become  extinct  unless  rescued  by  cultivation. 

Eucalyptus  globulus,  Blue  Gum,  peculiarly  valuable  in  swampy 
or  malarial  districts.  One  hundred  and  fifty  varieties  of 
Eucalyptus,  "  the  tree  of  the  future."  Cf.  article  in  Pop. 
Sci.  Mo.,  vol.  xii. :  "  The  Eucalyptus  of  the  Future,"  by 
Samuel  Lockwood.  See  also,  below,  list  by  W.  S.  Lyon. 

Eugenia  jambos,  Eose  Apple,  or  Jamrosade,  twenty  to  thirty 
feet,  should  be  cultivated  in  the  Southern  States  for  its 
delicious  fruit. 

Catalpa  bignonioides,  Walt.  Catalpa,  thirty  to  fifty  feet,  a  beau- 
tiful tree,  possessing  great  advantages  for  timber,  being 
the  cheapest  and  easiest  grown  of  all  our  forest  trees, 
native  or  introduced,  and  also  the  most  rapid  in  its  growth. 

Paulownia  imperial™,  Siebold.  A  grand  flowering-tree,  forty 
feet  high,  with  immense  leaves,  of  rapid  growth,  and  par- 


228  APPENDIX. 

ticularly  suited  for  parks,  road-sides,  and  shade  (from 
Japan),  has  large,  purple,  fragrant  pannicles  of  flowers  in 
the  spring. 

Schinus  molle,  the  Pepper-Tree,  or  Peruvian  Mastich-Tree. 
The  leaves  exude  an  oily  fluid,  filling  the  air  with  fra- 
grance, particularly  after  a  rain. 

Eriobotryajaponica,  the  Loquat,  or  Mespilus,  should  be  intro- 
duced into  the  Southern  States,  being  one  of  the  most 
grateful  acid  summer  fruits.  The  tree  is  a  very  hand- 
some, broad-leaved  evergreen. 

Oinnamomum  cam/phora,  the  common  Camphor-Tree  of  China. 
Growing  trees  can  be  had  at  the  Agricultural  Department, 
Washington,  D.  C. 

Dryobalanopos  aromatica,  the  Sumatra  Camphor- Tree.  Both 
of  these  should  be  introduced  and  cultivated  in  Cali- 
fornia. 

Aleurites  triloba,  Candle-Nut-Tree,  thirty  feet,  native  of  the 
Pacific  islands,  exceedingly  useful  for  its  oily  nuts. 

Ceratonia  Siliqua,  the  Carob,  or  St.  John's-Bread-Tree.  Could 
easily  be  cultivated  in  immense  numbers  from  seed,  as  is 
our  ordinary  locust-tree,  and  would  be  a  valuable  addition 
to  the  country,  as  it  would  furnish  a  large  amount  of 
food  for  cattle,  the  bread-bean  pods  being  used  for 
feeding  cattle  and  swine  in  all  countries  where  the  trees 
grow,  and  is  being  imported  largely  into  Europe  and 
England. 

Blighia  sapida,  the  Akee.  A  native  of  West  Africa,  but  be- 
coming widely  dispersed,  would  grow  in  the  more  South- 
ern States,  and  furnishes  a  valuable  fruit,  very  whole- 
some when  cooked. 


APPENDIX.  229 

Per  sea  gratissima,  or  Alvocada  Pear,  or  Alligator  Pear,  a  small 
tree,  bearing  large,  purplish,  pear-shaped  fruits,  much  es- 
teemed for  dessert.  Would  be  a  valuable  addition  to  the 
fruits  of  Southern  California. 

Prunus  amygdalus,  the  Almond,  fifteen  feet.  Already  culti- 
vated in  California. 

Carya  olivceformis,  N.  Pecan  Nut.  Is  proving  one  of  the 
most  valuable  trees  of  Texas;  recently  introduced  into 
Georgia ;  the  yield  of  nuts  is  large,  bringing  good  prices. 

Castanea  vesca,  Spanish  Chestnut.  The  tree  furnishes  a  large 
percentage  of  the  food  of  the  poorer  classes  of  Southern 
Europe,  and  its  cultivation  in  this  country  should  be  en- 
couraged. A  Japanese  "  Giant"  variety  has  been  lately 
introduced.  Said  to  be  of  better  flavor  than  the  Spanish 
chestnut. 

Juglans  regia,  English  Walnut,  or  Madeira  Nut,  sixty  feet, 
valuable  both  for  its  wood  and  its  nuts ;  the  yield  is  large, 
as  many  as  twenty-five  thousand  nuts  to  a  tree. 

Morus  alba,  White  Mulberry,  the  most  valuable  for  feeding 
silk-worms.  Its  cultivation  should  be  encouraged.  Sev- 
eral varieties  are  offered  by  the  nursery-men  for  the  large 
edible  fruit. 

Achras  sapota,  the  Sapodilla,  or  Naseberry,  a  very  sweet,  high- 
flavored  fruit.  Tree  spreading,  with  fine,  glossy  leaves. 

jEgle  marmelos,  the  Bael-fruit,  Elephant  Apple,  Maredoo,  or 
Bengal  Quince,  a  small  tree,  of  the  orange  family,  pro- 
ducing an  odd  fruit  and  trifoliate  leaves. 

Anacardium  occidental,  the  Cashew-nut.  A  tree  of  the  Tere- 
binth family,  attaining  considerable  size,  and  in  growth 
resembling  the  walnut.  The  curious  fruit  is  kidney-shaped, 
20 


230  APPENDIX. 

about  an  inch  long,  and  after  roasting  is  a  good  substitute 
for  almonds,  etc.,  at  table. 

Anona  cherimolia,  the  Cherimoya,  or  Jamaica  Apple,  a  loose, 
spreading  tree  of  the  Custon  Apple  family,  attaining  a 
height  of  twenty  to  twenty-five  feet.  The  light-green 
fruit  is  beautiful,  delicious,  and  considered  one  of  the 
finest  fruits  of  the  world. 

Anona  muricata,  Sour-Sop,  fifteen  to  twenty  feet  high,  fine 
glossy  foliage,  fruit  large,  heart-shaped  (six  to  nine  inches 
in  circumference),  green  and  prickly,  contains  a  fresh, 
agreeable,  sub-acid  juice. 

Chrysophyllum  cainifo,  the  Star  Apple.  A  tree  of  thirty  to  forty 
feet,  spreading  branches,  beautifully  veined  leaves,  silvery 
white  on  the  under-side,  fruit  about  the  size  of  an  apple, 
wholesome,  with  an  agreeable  sweet  flavor. 

Mcus  carica,  Fig.  Very  easy  of  cultivation,  and  offered  by 
the  nursery-men  in  several  varieties;  should  be  largely 
cultivated  in  California  and  all  our  Southern  States. 

Malpighia  glabra,  Barbadoes  Cherry.  One  of  the  favorite 
trees  of  the  Barbadoes  and  West  Indies,  usually  planted 
near  dwellings,  and  as  hedges.  The  trees  are  beautiful 
evergreens,  bearing  cherry-like  fruit  of  a  pleasant  taste. 

Mammea  Americana,  the  Mammea  Apple,  or  St.  Domingo 
Apricot,  sixty  to  seventy  feet  high,  with  broad,  ovate, 
shining  leaves ;  fruit  angular,  size  of  cocoanut,  with  juicy 
yellow  pulp  of  delicious  flavor. 

Mangifera  Indica,  the  Mango.  This  delightful  fruit  is  now 
being  introduced  largely  into  Florida.  It  is  of  very 
rapid  growth  and  fine  form ;  five  or  six  varieties  are 
offered  by  nursery-men. 


APPENDIX.  231 

See  "  Popular  Science,"  1879,  for  an  account  of  the  ameliora- 
tion of  climate  in  dry  barren  districts  by  this  tree. 

Psidium  Caltleyanum,  the  Cattley  or  Strawberry  Guava,  now 
being  much  cultivated  in  Florida,  is  of  fine  appearance, 
and  the  plum-like,  claret-colored-fruit  being  of  most 
agreeable  flavor. 

Punica  granatum,  the  Pomegranate.  Easily  grown  and  very 
handsome ;  small  trees,  flowers  showy.  One  of  the  most 
desirable  fruits.  Bark  of  the  tree  used  in  medicine. 

Psidium  Guaiava,  the  ordinary  Guava.  One  of  the  most  valua- 
ble fruits  for  jellies  and  preserving.  Several  varieties 
offered  by  nursery-men. 

Tamarindus  Indica,  the  Tamarind.  A  beautiful  tree  with  deli- 
cate blossoms,  and  soft,  pinnately  divided  leaves,  grows  to 
eighty  feet  in  height.  The  pods  pressed  in  syrup  or  sugar 
form  the  preserved  tamarind  of  commerce. 

Zizyphm  jujuba,  the  Jujuba.  A  small  tree  of  the  Buckthorn 
family,  bearing  small  yellow,  farinaceous,  delicious  berries. 
The  lotus  spoken  of  by  Pliny  as  furnishing  the  food  of 
the  ancient  Lybian  people  called  Lotophagi. 

Melia  azedarach,  L.  The  Bead-Tree,  or  Pride  of  India.  Beau- 
tiful for  streets  and  parks  of  our  Southern  cities ;  thirty  to 
forty  feet  high,  flowers  fine,  loose,  terminal,  lilac-like  spikes. 

Dichopsis  gutta.  The  Gutta-percha.  This  is  a  tree  of  the 
Star-apple  family,  attaining  a  height  of  from  sixty  to 
seventy  feet.  Leaves  smooth,  ovate,  rusty-brown  on  un- 
der-side. This  valuable  tree  is  rapidly  becoming  extinct 
in  its  native  habitations,  and  efforts  should  be  made  to 
introduce  it  into  all  tropical  and  subtropical  climates. 
The  French  government  has  recently  decided  to  cultivate 


232  APPENDIX. 

it  in  Algeria.    Why  should  it  not  be  introduced  into 
Southern  California? 

Mimusops  globosa.    The  Ballata.     Furnishes   a  milky  juice 
equal  to  the  best  gutta-percha  of  the  East.    This  should 
be  tried.     It  is  a  native  of  British  Guiana. 
Butyrospermum  ParMi,  the  Karite  or  Butter-Tree.    An  African 
tree,  furnishing  from  its  seeds  the  Shea-butter  of  com- 
merce, used  in  soap-making,  and  a  gum  or  coagulated 
juice  which  has  recently  been  found  to  be  equal  to  the 
best  gutta-percha.     It  is  possible  that  this  tree  might  be 
made  to  grow  in  the  warmer  parts  of  California. 
Cinchona  calisaya,  Cinchona  succirubra,  Cinchona  condaminea. 
These  three  species  of  cinchona  have  been  successfully 
cultivated  in  Mexico ;  in  the  Canton  of  Cordova  several 
thousand  cinchona-trees  exist  and  are  doing  well.    The 
beautiful  trees  with  large  velvety  leaves,  turning  red  when 
old,  may  be  seen  by  those  who  travel  by  rail  from  Vera 
Cruz  to  Mexico.    It  is  worthy  of  serious  effort  to  cultivate 
this  valuable  tree  in  Texas  and  California. 
Quillaja  saponacia,  Quillaia-bark  Tree,  Soap-bark  Tree.     This 
large  tree  (fifty  to  sixty  feet)  yields  in  its  bark  a  product 
very  valuable  in  cleaning  delicate  colored  fabrics,  and 
could  undoubtedly  be  grown  with  profit  in  California. 
The  sub-tropical  trees  mentioned  in  the  above  list  can  all 
be  obtained  from  the  nursery-men  (e.g.,  Siebrecht  &  Wadley, 
Eose-Hill  Nurseries,  New  Eochelle,  New  York),  or  of  the 
Agricultural  Bureau,  Washington,  D.  C.,  and  they  can  be 
successfully  grown    in    any  of  the  Southern    States   where 
the  winter  temperature  does  not  fall  below  45°  F.    I  have 
not  mentioned  many  well-known  varieties,  but  have  preferred 


APPENDIX.  233 

to  call  attention  to  such  little-known  trees  as  might  perhaps  be 
cultivated  (and,  in  fact,  are  already  to  some  extent  in  Florida 
and  California)  successfully,  with  profit  in  various  ways  to  our 

Southern  States. 

Very  respectfully  yours, 

C.  S.   DOLLEY. 

STATE  BOARD  OF  FORESTRY, 
Los  ANGELES,  CALIFORNIA,  June  6, 1892. 

PROF.  EDWIN  J.  HOUSTON, 

1809  Spring  Garden  St.,  Philadelphia,  Pa. 
DEAR  SIR, — I  send  you  a  few  "notes."  The  second  part 
will  deal  with  the  much  larger  subject  of  lands  outside  of  the 
natural  forest  districts,  suitable  only  for  forest  planting,  and 
the  species  we  find  most  useful  thereon.  Our  experiments 
with  these  are  practicable  and  tangible,  and  I  trust  will  prove 
of  more  value  than  the  "  glittering  generalities"  of  the  accom- 
panying Part  I. 

I  will  endeavor  within  a  week  to  give  you  the  balance. 

Very  truly  yours, 

WM.  S.  LYON. 


NOTES. 

PART  I. 

ON  TREES  SUITABLE  FOR  REFORESTATION  UPON  THE 
PACIFIC  COAST. 

There  are  portions  of  the  Sierra  Nevada  Mountains  which, 
by  the  various  processes  of  surface-mining,  have  been  denuded 
of  their  original  forest  cover,  as  well  as  of  every  vestige  of 
forest  floor, — i.  e.,  fertile  soil. 

20* 


234  APPENDIX. 

In  many  localities  the  areas  laid  bare  amount  to  hundreds 
of  acres  in  single  tracts. 

In  portions  of  Amador  and  Calaveras  Counties,  multitudes 
of  "prospects"  join  each  other,  extending  for  miles  upon  a 
so-called  "  river-bar." 

These  "  prospects"  are  frequently  only  holes  that  have  been 
excavated  from  four  to  ten  feet  in  depth,  and  the  auriferous 
gravel  thrown  out  and  scattered  far  enough  to  nearly  com- 
pletely cover  the  original  surface  soil  for  from  one  to  ten  inches. 

In  Placer  and  Nevada  Counties  the  process  of  hydraulic 
mining  has  generally  washed  out  vast  flats  or  valleys  in  the 
mountains,  and  leaving  the  resulting  basin  covered  chiefly 
with  gravel,  boulders,  or  blue  clay. 

These  operations  have  been  discontinued  in  some  localities 
for  now  more  than  thirty  years ;  in  others,  only  recently. 

Yet  in  all  of  them,  and  apparently  with  an  utter  dearth  of 
soil,  the  native  timber  is  making  an  effort  to  assert  itself. 

At  Dutch  Flat,  where  gigantic  mining  operations  have  only 
ceased  during  three  years,  a  very  sparse  setting  of  small 
Psuedotsuga  Douglasii,  Pinus  tuberculata,  Libdocedrus  decurrens, 
and  Pinus  Sabinana  have  established  themselves.  The  same 
features  exist  upon  the  Mokelumne  Kiver,  in  Calaveras  County, 
where  no  mechanical  disturbance  has  occurred  since  the 
original  covering  up  of  the  soil  thirty  years  before. 

Both  localities  are  between  three  thousand  and  three  thou- 
sand six  hundred  feet  in  elevation,  and  the  timber  is  such  as 
belongs  to  that  elevation  in  the  Sierras. 

The  uninjured  timber  in  the  more  southern  county  and 
adjoining  denuded  lands,  can  only  be  described  as  scrubby; 
and  1  cannot  say  that  that  which  has  established  itself  upon 


APPENDIX.  235 

the  worked-over  sites  has  been  notably  depauperized  by  its 
mulch  of  clay  and  gravel.  At  the  point  of  southern  observa- 
tion Abies  concolor  occurs,  and  seems  to  thrive. 

I  noted  with  interest  that  young  plants  of  the  Douglas 
spruce,  growing  about  denuded  fields  in  Nevada  County,  at 
three  thousand  five  hundred  feet,  showed  great  vigor,  although 
naturally  fine  specimens  (mature)  seldom  occur  in  the  prim- 
itive forest  below  five  thousand  feet. 

It  occurs  to  me  that  this  is  an  index  that  this  plant  may 
prove  valuable  for  future  systematic  reforestation.  The  other 
species  named,  except  for  purposes  of  forest  cover,  are  not 
held  in  much  esteem  by  lumbermen.  At  higher  altitudes,  and 
in  the  regions  covering  our  valuable  pines  and  spruces,  extend- 
ing over  nearly  seven  hundred  miles  from  San  Bernardino  to 
Plumas  County,  no  mining  operations  (surface)  have  been 
conducted,  and,  except  in  isolated  cases  of  torrential  erosions, 
the  forest  floor  is  intact. 

The  original  cover  has  been,  however,  heavily  cut  and 
burned  over.  Their  native  reproductive  powers  seem  in- 
destructible. 

Where  deforestation  has  been  caused  by  the  axe,  a  full 
proportion  of  young  growths  of  Pinm  lambertiana,  P.  Coulteri, 
P.  Jeffreyi.  P.  ponderosa,  and  Psuedotsuga  Douglasii  seem  to 
follow. 

Where  the  denudation  has  occurred  from  fire,  the  more 
relatively  worthless  White  Fir,  Flat-leaved  Cedar,  and  Hem- 
lock seem  to  preponderate. 

In  the  mountains, — i.  e.,  the  natural  timber  district  of  the 
State, — not  a  single  instance  occurs  where  reforestation,  upon 
any  scale,  large  or  small,  has  been  undertaken. 


236  APPENDIX. 

No  attempt  or  experiment  with  exotic  species  has  ever  been 
tried  within  the  timber  belt,  and  the  values  of  the  endemic 
species,  and  their  readiness  to  conform  to  such  unpromising 
situations  as  those  described,  justify  us  in  thinking  that  they 
will  best  fulfil  future  systematic  mountain  reforestation. 

PART    II. 

SPECIES  USEFUL  FOR  REFORESTATION  OF  FOOT-HILL-LANDS, 
WASHES,  OR  LANDS  UNSUITABLE  FOR  GENERAL  AGRI- 
CULTURE IN  CALIFORNIA. 

(A)  Endemic  Species. 

First  among  them  I  rate  the  Pinus  insignis,  or  Monterey 
Pine.  Naturally  restricted  to  a  narrow  strip  of  land  upon  the 
Mid-California  seaboard,  not  extending  inland  more  than  ten 
miles,  it  has  taken  kindly  to  transplantation  to  the  interior 
hotter,  drier  valleys  for  more  than  one  hundred  miles  from 
the  sea.  It  rarely  exceeds  a  height  of  thirty  metres ;  the  tim- 
ber is  generally  twisted,  coarse  in  grain,  deficient  in  strength, 
not  durable,  and  rates  low  for  either  lumber  or  fuel  uses.  Its 
pre-eminent  value  is  as  a  forest  cover  and  wide  adaptability  to 
soil  and  climate. 

Extensive  plantations  upon  arid,  gravelly  hill-sides,  without 
care  or  cultivation,  have  attained  an  average  height  of  twelve 
feet  in  five  years  from  the  seed,  and  isolated  specimens  have 
made  a  growth  of  sixteen  feet  during  that  time.  It  resists 
fire  well,  young  plantations  where  badly  burned  over — i.e.,  with 
three-quarters  of  the  foliage  destroyed — generally  recuperating. 

Cupressus  macrocarpa,  a  smaller  tree,  fifty  to  seventy  feet, 
nearly  as  local  as  the  Pinus  insignis,  of  still  more  rapid  devel- 


APPENDIX.  237 

opment,  of  more  widely-tried  distribution,  and  adapted  to  soils 
lacking  in  fertility ;  thrives  wherever  our  rainfall  reaches  an 
average  of  sixteen  inches,  and  resists  extreme  summer  heat 
well ;  holds  its  lower  branches  and  foliage  with  tenacity  to  a 
great  age,  making  it  serviceable  for  wind-breaks  or  ornamental 
hedging;  the  wood  is  light,  but  extremely  durable  under- 
ground, making  it  valuable  for  posts.  Its  small  size  makes  it 
unavailable  for  general  lumbering  uses,  other  than  as  a  cabinet 
wood,  for  which  it  is  well  adapted. 

These  two  are  the  only  native  conifers  that  have  been  suc- 
cessfully planted  upon  lands  deficient  in  moisture  and  fertility, 
upon  a  scale,  and  over  a  period  of  time  prolonged  enough,  to 
assert  that  they  will  prove  valuable  for  our  so-called  arid 
hill-sides. 

In  a  more  experimental  way,  upon  more  restricted  areas, 
away  from  their  native  habitats,  the  subjoined  coniferous  spe- 
cies have  been  planted,  and  success  has  only  followed  where 
the  soil  was  of  reasonable  depth,  fair  fertility,  and  where  water 
was  not  remote  from  the  surface.  Such  plantations  have 
proven  successful  in  the  northern  part  of  the  State  where  water 
surface  was  distant,  but  only  where  the  average  annual  rain- 
fall exceeds  twenty  inches,  and  where  the  plantations  have 
been  made  in  nooks  and  valleys  sheltered  from  drying  winds. 

In  the  southern  half  of  the  State,  these  conditions  are  not 
sufficient,  and  a  deeply-cut,  well-sheltered,  canon  canying 
water  upon  or  near  the  surface  is  a  sine  qua  non. 

The  species  are : 

Sequoia  sempervirens. 

Sequoia  gigantea. 

Chamcecyparis  Lawsoniana. 


238  APPENDIX. 

All  these  are  species  reaching  heroic  dimensions,  and  the 
first  and  last  rank  in  the  very  first  class  as  unsurpassed  timber 
trees. 

The  limits  of  their  utility  for  forest  planting  is,  owing  to  the 
conditions  stated  above,  restricted  to  very  narrow  limits. 

Pinus  Sabiniana  and  Juniperus  California  both  extend  into 
the  lower  foot-hills,  and  naturally  occur  upon  barren,  stony 
lands  of  poorest  quality ;  and  though  nothing  more  than  occa- 
sional experimental  tests  have  been  made,  no  question  or 
doubt  as  to  their  utility  upon  utterly  waste  lands  exists. 

Their  relatively  slower  growth,  and  inferior  fuel  and  timber 
value,  to  the  Monterey  pine  and  Monterey  cypress,  explain 
their  neglect,  rather  than  any  doubt  as  to  their  successful 
development. 

For  points  where  the  conditions  of  soil  and  climate  discour- 
age the  planting  of  the  latter,  these  two  species  can  be  success- 
fully introduced. 

Of  our  native  oaks,  occasional  tests  have  been  made  with  a 
few  species.  The  most  valuable,  the  Quereus  densiflora,  makes 
but  poor  growth  outside  of  humid  and  elevated  ravines.  Quer- 
cus  lobata  demands  soil  of  both  depth  and  fertility.  Under 
these  conditions  it  makes  phenomenal  growth.  I  have  cut  a 
tree  displaying  but  forty-five  annular  rings,  that  measured  four 
feet  ten  inches  in  diameter  above  any  buttress. 

Quercus  agrifolia  has  proven  most  tractable  of  all  upon  dry, 
stony  sites.  Transplants  easily,  and  after  establishment  makes 
fairly  rapid  growth.  Its  rather  small  size  is  an  objection.  The 
timber  is  inferior,  stands  but  little  transverse  strain,  but  yields 
a  superior  fuel. 

With  our  other  trees  no  transplantations  other  than  orna- 


APPENDIX.  239 

mental  have  been  made  of  those  extending  below  the  conif- 
erous timber  belt. 

Chief  among  them,  the  Oregon  ash,  Oregon  maple,  syca- 
more, cotton-wood,  and  laurel  occur  mostly  in  cafions,  and 
with  the  exceptions  noted  are  unsuitable  for  general  planting. 

The  cotton-wood,  Populus  Fremontii,  has  shown  (on  a  large 
scale)  conformability  to  the  lands  strongly  alkaline.  Such  are 
waste  lands  for  this  purpose,  as  the  process  of  reclamation  is 
tedious  and  costly.  They  comprise  many  thousands  of  acres 
of  our  West  Coast  bottoms,  and  no  tree  outside  of  this  cotton- 
wood  and  Tamarix  gallica  (exotic)  that  has  been  tested  upon 
them  has  heretofore  proven  satisfactory.  Growth  quick ;  timber 
warps  badly ;  rates  low  for  fuel. 

The  Laurel,  Umbellularia  Galifornica,  has  been  attempted 
away  from  water-courses,  with  some  measure  of  success.  The 
timber  is  invaluable  for  veneers,  exceedingly  hard  and  heavy, 
and  excels  the  cherry  and  redwood  burl  in  beauty,  but  is  of 
such  exceedingly  slow  growth  that  few  attempts  have  been 
made  looking  to  its  extended  planting. 

PART   III. 
(B)  Exotic  Species. 

Considerable  plantations  have  been  made  throughout  the 
State  with  Eucalyptus  species. 

These  in  size  range  from  one  to  four  hundred  acres.  Plan- 
tations have  been  made  with  some  fifty  species,  but  ninety  per 
cent,  embrace, — 

No.  1,  Eucalyptus  globulus. 

Nine  per  cent,  are  of 

No.  2,  Eucalyptus  rostrata,  and 


240  APPENDIX. 

No.  3,  Eucalyptus  virinalis,  and  less  than  one  per  cent,  of 
the  other  species. 

No.  I,  by  reason  of  its  more  rapid  growth,  has  been  most 
freely  planted.  It  is  confined  to  the  thermal  belt,  suffering 
when  young  from  low  temperatures  (2°  to  4°  F.  of  frost). 
Nos.  2  and  3  are  much  hardier,  and  are  equally  resistant  of 
drought. 

All  will  grow  upon  arid  hills,  but  only  make  remunerative 
growth  where  the  subsoil  is  of  an  open,  porous  nature ;  the 
root  must  have  an  opportunity  to  get  down.  Upon  rock  or 
impervious  subsoils  these  three  gums  may  be  seen,  fairly 
vigorous,  but  not  averaging  over  twelve  to  fifteen  feet,  now 
with  stem  diameter  of  over  two  and  a  half  inches,  representing 
five  and  six  years'  growth.  Eesults  about  equal  to  one  year 
upon  open,  porous  soils  of  fair  quality. 

In  value  for  fuel  or  timber,  they  take  precedence  as 
follows : 

E.  rostrata,  1. 

"  globulus,  2. 

"  virinalis,  3. 

The  former  is  reputed  to  be  "  teredo"-proof ;  but  there  is 
no  timber  as  yet  within  the  State  large  enough  for  wharf 
purposes. 

In  a  smaller  way,  tests  have  been  made  with  other  species ; 
the  following  prove  of  greatest  merit : 

Euc.  corynocalyx  (Sugar  Gum).  Hard  and  durable  timber. 
Tree  umbrageous,  endures  drought  and  sterile  soils.  Suscepti- 
ble to  light  frosts. 

Euc.  diversicolor,  characteristics  not  dissimilar  from  last. 

Euc.  populi  folia,  smaller  tree  than  last,  but  hardier. 


APPENDIX.  241 

Euc.  leucoxylon,  rose-flowered  variety,  and 

Euc.  amygdalina,  var.  angusti/olia,  are  the  only  two  species 
that  extend  beyond  our  extra- tropical  limits,  having  success- 
fully withstood  the  cold  of  16°  F. 

Have  not  seen  the  E.  amygdalina  tested  upon  poor  soils. 
The  former,  however,  is  very  tenacious  of  life  upon  dry  and 
poor  lands. 

Both  make  trees  of  the  greatest  magnitude. 

In  cultivable  lands,  Euc.  Gunni  will  make  more  rapid  growth 
than  E.  globulus,  and  hence  is  profitable  for  a  fuel  crop  that 
can  be  cut  every  four  years. 

A  few  other  promising  sorts  are, — 

E.  citriodora,  for  its  essential  oil.    Dry  exposures. 

E.  paniculata.    Dry  exposures. 

E.  punctata.    Dry  exposures. 

Most  species  of  Eucalypti  make  good  fuel ;  a  few  are  very 
durable  under  ground  or  in  water,  and  though  largely  used 
in  the  antipodes  for  railway  building,  ties,  etc.,  are  in  dis- 
repute here  from  the  tendency  of  some  species  to  check  and 
warp,  disabilities  that  can  be  overcome  by  cutting  in  proper 
season  and  reasonable  attempts  at  curing. 

Acacias. 

Upon  any  soil  non-alkaline,  and  wherever  the  rainfall  ap- 
proximates sixteen  inches,  these  are  indicated  for  general 
forest  uses. 

They  require  but  little  assistance  to  be  established,  attain 
marketable  size  in  five  to  eight  years,  furnish  an  excellent  fuel 
(wood  too  small  for  most  economic  purposes),  and  some  excel 
all  other  trees  in  the  quantity  and  quality  of  superior  tan- 
bark  yielded  to  the  acre.  They  have  been  fairly  tested  upon 
L  q  21 


242  APPENDIX. 

hill,  valley,  and  brush  lands,  where  cultivation  was  impracti- 
cable ;  the  results  have  been  promising,  although,  like  the 
eucalypti,  a  measurable  and  perhaps  profitable  increment  in 
growth  has  followed  the  cost  of  cultivation. 

The  most  valuable  species — i.e.,  the  one  richest  in  tannin — is 
the  Acacia  pycnantha.  It  is,  however,  more  sensitive  to  cold 
than  some  others,  and  hence  properly  restricted  to  the  thermal 
section  of  the  coast. 

The  next  in  value.  A.  decurrens,  and  its  immediate  congener, 
A.  moligsima,  are  suitable  for  a  very  wide  range,  thriving  in 
the  littoral  regions,  as  well  as  for  one  hundred  miles  inland, 
and  for  a  length  of  seven  hundred  miles  north  and  south. 

A.  melanoxylon  is  less  valuable  for  its  tan-bark,  but  makes  a 
larger  tree  (twenty  metres),  and  furnishes  a  valuable  cooper's 
wood  and  the  best  fuel.  It  requires,  perhaps,  more  moisture 
and  a  better  soil  than  the  other  species  to  obtain  its  maximum 
growth.  Incidentally  it  is  compact  and  symmetrical  in  habit, 
hence  serving  well  for  wind-breaks  or  street-planting. 

Casuarinas  of  different  sorts  have  been  fairly  tried.  Among 
them  C.  stricta,  C.  teniusimus,  C.  suberosa,  and  C.  equisitaostolia. 
All  are  rapid  growers  and  hardy,  also  adapted  to  arid  sites. 

The  last-named  has  given  larger  evidence  of  versatile  adapt- 
ability to  our  requirements  of  soil  and  climate. 

Allied  to  the  acacias  we  have  a  tree  of  phenomenally  rapid 
growth,  and  conformable  to  waste  lands.  It  is  Albizzia  lo- 
phantha.  It  is  of  no  possible  economic  value  except  for  the 
marvellous  rapidity  with  which  it  furnishes  forest  cover,  and 
is  thus  rendered  available  for  furnishing  a  quick  and  short- 
lived protection  to  coniferous  plantations. 

Eastern  United  States  Silva  have  been  but  sparingly  at- 


APPENDIX.  243 

tempted.  Reasonable  success  has  followed  the  planting  of 
both  Catalpa  and  Robina  psuedo  Acacia  in  the  northern  half 
of  the  State.  In  the  south  they  exigently  demand  soil  of 
greater  depth  and  fertility  than  we  are  willing  to  classify  as 
forest  lands.  The  same  holds  true  of  most  of  the  nut-bearers, 
the  Caryas  and  allies,  although  sporadic  and  unprofitable 
attempts  have  been  made  with  the  English,  the  Black  Walnut, 
and  the  Pistachio. 

Some  plantations  of  Pinus  pinaster  give  promise  of  doing 
well,  remote  from  the  seaboard,  and,  to  a  limited  extent,  P. 
Austriaca,  P.  strobus,  P.  cembra,  and  P.  Laricio  have  been 
planted. 

Results,  as  far  as  obtained,  indicate  unsatisfactory  growth, 
although  the  limited  period  of  observation  makes  it  premature 
to  formulate  any  conclusions. 

Isolated  cases  exist  of  above  fifty  additional  exotic  species 
that  have  been  planted  for  forest  uses. 

The  data  is  sufficient  to  furnish  material  that  is  not  largely 
hypothetical. 

If  such  be  desired,  a  synoptical  list  can  be  supplied. 

WILLIAM  S.  LYON. 


INDEX. 


A. 

Agricultural  districts,  necessity  for 
preservation  of  trees  in,  14,  15. 

Agriculture,  demands  of,  for  re- 
moval of  forests,  11. 

Aims  of  forestry,  10. 

Air,  changes  in  composition  of,  ef- 
fects of,  on  earth's  life,  166,  167. 

Alps  of  Provence,  Marsh  on,  115, 
116. 

Amazon,  forest  lands  of,  28. 

Animal  and  vegetable  kingdoms, 
wonderful  balance  in  the  compo- 
sition of  the  atmosphere  insured 
by,  142. 

Animals,  minerals  and  plants,  mu- 
tual interdependence  between, 
168. 

Animals,  necessity  for  oxygen  in 
respiration  of,  141. 

Animate  enemies  of  the  forest,  64, 
71  to  76. 

Annual  Report  of  New  York  For- 
estry Commission,  extract  from, 
18,  19. 

Assimilation,  definition  of,  22. 

Atmosphere,  composition  of,  140. 
different  composition  of,  in  ge- 
ological past,  143,  144. 
heat  received  from  the  heated 

earth,  119. 

heat  received  from  the  sun  by 
absorption,  119. 


Atmosphere,  manner  in  which  it 
receives  heat  from  the  sun, 
119. 

possible  danger  from  disturb- 
ance of   composition   of,  by 
removal  of  forests,  144,  145. 
purification  of,  140  to  145. 
Avalanche,  influence  of,  in  destruc- 
tion of  forests,  67. 
Axe    of  pioneer,    a    badly- chosen 
emblem  of  civilization,  85. 


Balance  of  nature,  164  to  173. 
Bannwoelder,  67,  68. 
Basin  of  river,  definition  of,  111. 
Beavers,  destruction  of  forests  by, 

73. 

Beech  plum,  story  of,  35,  36. 
Beetles,  destruction  of  forests  by,  75. 


Calcareous  soils,  definition  of,  51. 
Carbonic  acid,  decomposition  of,  in 
plants  by  sunshine,  22. 

influence  of,  on  growth  of 
plants,  22. 

influence  of,  when  dis- 
solved in  water,  in  dis- 
integration of  rocks,  55. 

necessity  of,  for  existence 
of  plants,  142. 

of  atmosphere,  use  of,  140. 


21* 


246 


246 


INDEX. 


Carboniferous  period,   composition 

of  the  atmosphere  during,  144. 
Caterpillars,  destruction  of  forests 

by,  73,  74. 
Cause  of  deserts,  42. 

of  meadows  and  prairies,  43. 
of  steppe  regions,  43. 
Classes  of  land  suitable  for  main- 
tenance of  forests,  158,  159. 
Clayey  soils,  definition  of,  50,  51. 
Climate,  definition  of,  119. 

influence  of  elevation  of  land 

on,  121,  122. 
influence  of   land  and  water 

areas  on,  120,  121. 
influence  of   the  presence  of 

the  forest  on,  127  to  133. 
influences  producing  variations 

in,  120,  121, 122. 
of  forest  region,  characteristics 

of,  124. 

peculiarities  of  continental,  123. 
peculiarities  of  oceanic,  123. 
Comparative  unimportance  of  soil 

for  plant  growth,  25. 
Conditions  influencing  the  rapidity 
of  spread  of  forest  fires,  65, 
66. 
necessary  for  the  growth   of 

plants,  20  to  24. 
necessary  for  the  growth  of 

trees,  42  to  47. 
required  for  the  production  of 

rain,  101. 

Continental  climate,  peculiarities 
of,  123. 

D. 

Dana,  James  D.,  extract  from  his 
"  Manual  of  Geology,"  70,  145, 
146. 


Decaying  leaves,   influence  of,  on 

disintegration  of  rocks,  57. 
Decomposition  of  carbonic  acid  in 

plants  by  sunshine,  22. 
Definition  of  assimilation,  32. 

of  forestry,  9. 

Deforestation  and  reforestation,  14. 
Deserts,  cause  of,  42. 
Destruction  of  forests,  81  to  86. 
by  fire,  64,  65,  66. 
evil  results  following, 

81,  82. 
Disintegration   of   rocks,   agencies 

causing,  52,  53. 

Distant  planets,  possibilities  as  to 
the  existence  of  life  thereon,  98. 
Distinctive  flora  of  particular  re- 
gions, meaning  of,  30. 
Distribution  of  heat,  influence  of, 
by  destruction  of  forests,  84. 
of  solar  energy,  how  affected, 

170,  171. 
Domestic  and   domesticated  plant 

species,  33. 
Drainage,  109  to  113. 
definition  of,  109. 
influence  of  mountains  on,  16. 
surface,  definition  of,  110. 
underground,  definition  of,  110. 
Droughts,  caused  by  destruction  of 

forests,  81. 

E. 

Earth's  ocean  of  vapor,  90  to  97. 

Earthworm,  influence  of,  in  forma- 
tion of  soil,  56. 

Egyptian  mummies,  reputed  pres- 
ervation of  plant  seeds  in,  33. 

Electrical  theory  of  hail,  149,  150 

Equatorial  currents  of  air,  why 
rain-bearing,  101. 


INDEX. 


247 


Equatorial  land  areas,  effect  of,  on 

earth's  climate,  166. 
Erosion,  definition  of,  54. 

influence  of,  in  the  formation 

of  soil,  53. 

Evaporation,    circumstances   influ- 
encing rapidity  of,  90,  91,  92. 
of    moisture,    inconstancy    of, 

171,  172. 

Excavations,  growth  of  plants  on 
exposure  of  soil  brought  up  by, 
35. 

Excessive  multiplication  of  life, 
how  avoided,  169,  170. 

F. 

Feldspathic  rocks,  clayey  soils  de- 
rived from,  51. 

Fernow,   B.  E.,  definition  of  for- 
estry, 17. 
Fire,  destruction  of  forests  by,  64, 

65,  66. 

Fire-weed,   curious   conditions   re- 
quired for  germination  of,  37. 
Flammarion,  Camille,  extract  from 

"  The  Atmosphere,"  125,  126. 
Flora,  definition  of,  26. 

effect  of  elevation  on,  48,  49. 
effects  of    the  distribution   of 
heat,  light,  and  moisture  on, 
26. 
influence  of  temperature   on, 

31. 

on  mountain  slopes,  why  differ- 
ent at  different  altitudes,  26, 
27. 
Forest,  animate  enemies  of,  64,  71 

to  76. 

areas,  intelligent  protection  of, 
13. 


Forest,  climate,  characteristics  of, 

128. 

fires,  conditions  influencing  the 
rapidity  of  spread  of, 
65,  66. 

how  started,  65. 
inanimate  enemies  of,  61  to  67. 
influence  of  area  on  absorption 

of  heat,  127. 
influence  of  forest  area  on  loss 

of  heat,  128. 
influence  of   presence  of,    on 

climate,  127  to  133. 
lands  of  the  Amazon,  28 
preserves,  14. 
Forestry,  aims  of,  10. 

associations,  field  for,  10,  13. 
definition  of,  9. 
Fernow's  definition  of,  17. 
laws,  necessity  for,  10,  13. 
mistaken  ideas  concerning,  13. 
Forests,  dependence  of,  on  climatic 

conditions,  62. 
destruction  of,  81  to  86. 
by  beavers,  73. 
by  beetles,  74. 
by  caterpillars,  73,  74. 
by  goats,  73. 
by   grasshoppers,  73, 

74. 

by  insects,  73,  74. 
by  man,  75,  76. 
by  mice,  78. 
by  typographer  bee- 
tle, 75. 
distribution  of  heat,  influence 

of,  by  destruction  of,  84. 
disturbance  of  the  balance  of 
nature   affected  by  removal 
of,  172,  173. 


248 


INDEX. 


Forest,  droughts  produced  by  de- 
struction of,  81. 

encroachments  on,  necessity 
for,  11. 

influence  of  avalanches  in  de- 
struction of,  67. 

influence  of  inundations  in 
destruction  of,  66. 

influence  of,  on  humidity  of 
air,  97. 

influence  of,  on  natural  drain- 
age, 113.  . 

influence  of,  on  preventing 
disastrous  frosts,  130,  131. 

influence  of,  on  rapidity  of 
evaporation,  97. 

influence  of  parasitic  plants  on 
destruction  of,  71,  72. 

influence  of  rodents  on  destruc- 
tion of,  73. 

influence  of  torrents  on  de- 
struction of,  58. 

influence  of  wind  on  destruc- 
tion of,  66. 

inundations  produced  by  de- 
struction of,  81. 

loss  of  soil  following  destruc- 
tion of,  81. 

malarious  diseases  produced  by 
destruction  of,  82. 

natural  drainage  disturbed  by 
destruction  of,  82. 

necessity  for  preservation  of 
exact  balance  of  conditions 
to  existence  of,  63. 

necessity  for  removal  of,  11. 

of  mountain  slopes,  46. 

influence  of,  on 
rapidity  of 
drainage,  104. 


Forest  of  tropical  regions,  46. 

peculiar  distribution  of  moist- 
ure causing,  43. 
products  of,  11. 
protection  afforded  by,  against 

frosts,  129. 

why  a  regular  distribution 
of  moisture  is  requisite  for 
growth  of,  44,  45. 
why  the  air  of,  is  cooler  and 
damper  in  summer  than  air 
over  open  fields  in  same 
district,  132. 

Formation  of  soil,  50  to  57. 
Freezing  and   melting  of  ice,  in- 
fluence of,  on  disintegration  of 
rocks,  52,  53. 


Gases,  absorption  of,  by  soils,  56. 
Geikie,     Archibald,    extract    from 
"Text-Book    of    Geol- 
ogy," 60,  78,  88,  133. 
Germ,  necessity  for  existence  of,  for 

plant  life,  23. 

Germ-cell,  protoplasm  of,  20. 
Germs  of  plants,  source  of,  21. 

wonderful  vitality  of, 

21,  33,  34,  35,  36. 
of  seeds,  wonderful  vitality  of, 

33,  34,  35,  36. 
Glaciers,  definition  of,  54 

influence  of,  in  formation  of 

soil,  54,  59. 
Goats,  destruction  of  the  forests  by, 

73. 
Grasshoppers,  destruction  of  forests 

by,  73,  74. 
Gravelly  soils,  definition  of,  50. 


INDEX. 


249 


Guyot,      Arnold,      extract      from 
"  Earth  and  Man,"  28,  29,  48. 

H. 

Hail,  147  to  152. 

influence  of  destruction  of 
forest  on  occurrence  of, 
147. 

Volta's  theory  of,  149,  150. 
Hail-rods,  150. 
Hailstones,  structural  peculiarities 

of,  148. 

varying  sizes  of,  148,  149. 
Hail-storms,   damages   caused  by, 

151. 

electrical  phenomena  of,  148. 
rate    of     the    wind    during, 

151. 

Hartt,    Ch.    Fred.,    extract    from 
"  The  Geology  and  Physical  Ge- 
ography of  Brazil,"  137,  138. 
Heat  and  light,   necessity   of,  for 

plant  growth,  24. 
energy,   disappearance  of,  on 
evaporation  of  water,  95. 
liberation  of,  on   conden- 
sation of  vapor,  95. 
units,  95. 

Hough,  Franklin  B.,  extract  from 
"  Report  on  For- 
estry," 76,  77,  78. 
extract  from  the  "  Re- 
port of  the  United 
States  Commission- 
ers for  1877,"  159 
to  16o. 

extract  from  "  Report 
of  United  States 
Commissioners  of 
Forestry,"  135, 136. 


Houston,  Edwin  J.,  extract  from 
"Elements  of  Physical  Geogra- 
phy," 29,  30,  86,  87. 

Humboldt,  Alexander  von,  extract 
from  "  Cosmos,"  99,  104,  105. 

Humidity  of  air,  influence  of,  on 
evaporation,  92. 

Huxley,  T.  H.,  extract  from 
"  Physiography,"  106. 

Hydrogen,  in  plant  tissues,  source 
of,  23. 

Hydroscopic  properties  of  soils,  56. 

I. 

Inanimate   enemies  of  the  forest, 

61  to  67. 

Influence  of  mountains  on  drain- 
age, 16. 
Insects,  destruction  of  forests  by, 

73,  74. 
larvae  of,  destruction  of  forests 

by,  74. 

Interests  of   lumbermen   and  for- 
estry associations  mutual,  18. 
Inundations  caused  by  destruction 

of  forests,  81,  82,  83. 
causes    of,    81,    82,    83,    111, 

112. 
influence  of,  on  destruction  of 

forests,  66. 

influence  of  the  surface  on  the 
number  and  severity  of,  1 12. 
Island  of  St.  Helena,  Lyell  on  the 
destruction  of  its  forests,  87. 


J. 

Jack  Sprat,  of  nursery  lore,  143. 
"  Journal  of  the  Society  of  Arts," 
extract  from,  89. 


250 


INDEX. 


Land  and  water  areas,  exact  bal- 
ance between,  165. 

Lands  suitable  for  preserving  forests 
on,  15. 

Le  Conte,  Joseph,  extract  from 
"  Elements  of  Geology,"  59. 

Lindley,  John,  extract  from  his 
"  Botany,"  39  to  41. 

Loomis,  Elias,  extract  from  "  Trea- 
tise on  Meteorology,"  152,  153. 

Lyell,  Charles,  extract  from  "  Prin- 
ciples of  Geology,"  69,  87,  114, 

115. 

M. 

Mackenzie  River,  raft  in,  67. 

Malarious  diseases  produced  by  de- 
struction of  the  forests,  82. 

Man,  destruction  of  forests  by,  75, 
76. 

Marsh,  George  P.,  extract  from 
"The  Earth  as  Modified  by  Hu- 
man Action,"  38,  89,  58,  115, 
116,  173,  174,  175,  176. 

Matter,  organic  and  inorganic,  dis- 
tinction between,  29. 

Maury,  M.  F.,  extract  from  "  Phys- 
ical Geography,"  107,  108. 

Meadows  and  prairies,  peculiar  dis- 
tribution of  moisture  causing,  43. 

Method,  nature's,  of  distributing 
plant  germs,  32. 

Mice,  destruction  of  forests  by,  78. 

Mineral  matters,  necessity  of,  for 

plant  growth,  25. 
source  of,  in  plant  tissues, 
23. 

Minerals,  plants  and  animals,  mu- 
tual interdependence  between, 
168. 


Mississippi  River,  raft  in,  67. 

rafts,  Lyell  on,  69. 
Moist  air  of  forest,  influence  of,  on 

absorption  of  heat,  130. 
Moisture,   effect  of   variations    in 
amount,   on   character    and 
distribution  on  flora,  42. 
how  absorbed  by  plants,  22. 
of  atmosphere,  use  of,  141. 
principal  food  of  plants,  22. 
Mountain  rains,  how  caused,  102. 
slopes,  forests  of,  46. 

necessity  for  preservation 

of  forests  on,  47. 
Mountains  the  birthplaces  of  rivers, 

47,  103, 104. 
the  natural  home  of  the  forest, 

reasons  for,  15,  16,  17. 
the  natural  home  of  the  rivers, 

16. 

Mud-flats,  damages  produced  by,  84. 
Mutual  interests  of  forestry  associ- 
ations and  lumbermen,  18. 

N. 

Natural    drainage,    damages    pro- 
duced by  the  disturbance 
of,  112. 
disturbed    by   destruction 

of  forests,  82. 

Nature,  balance  of,  164  to  173. 
Necessity  for  preservation  of   for- 
ests on  mountain  slopes,  47, 
of  germs  for  the  existence  of 

plants,  23. 
of  oxygen  for  growth  of  plants, 

23. 

New  York  Forestry  Commission, 
extract  from  Annual  Report  of, 
18,  19. 


INDEX. 


251 


o. 

Oceanic  climate,    peculiarities    of, 

123. 

Oxygen  of  atmosphere,  use  of,  140. 
necessity  for,  in  respiration  of 
animals,  141. 

P. 

ParagrSles,  150. 

Parasitic  plants,   influence   of,   in 

destruction  of  forests,  71,  72. 
Peaty  soils,  definition  of,  51. 
Pine   forests,   appearance  of  scrub 

oak  on  burning  over  of,  36,  37. 
Plant  germs,  nature's  method  of 

distributing,  32. 
wide  distribution  of,  32  to 

38. 
wonderful  vitality  of,  33, 

34,  35,  36. 
nationality,  26. 
seeds,    wonderful    vitality    of, 

33,  34,  35,  36. 
Planting  of  trees,  when  advisable, 

157. 

Plants,  animals,  and  minerals,  mu- 
tual    interdependence     be- 
tween, 168. 
conditions    necessary   for    the 

growth  of,  20  to  24. 
decaying,  influence  of,  in  for- 
mation of  soil,  50. 
necessity  of  oxygen  for  growth 

of,  23. 

source  of  germs  of,  21. 
source  of  seeds  of,  21. 
Polar  currents  of  air,  why  generally 

drought- producing,  101. 
land  areas,  effect  of,  on  earth's 
climate,  167. 


Prairies,  new  growth  of  plants 
marking  wagon-tracks  on,  36. 

Precipitation,  forms  of,  100. 

Pressure  of  air,  influence  of,  on 
rapidity  of  evaporation,  92. 

Prestwich,  Joseph,  extract  from 
"Geology,  Chemical,  Physical, 
and  Stratigraphical,"  117,  118. 

Products  of  the  forests,  11. 

Protoids,  definition  of,  29. 

Protoplasm  of  germ-cell,  20. 

Pouchet,  extract  from  "  The  Uni- 
verse," 78,  79,  80. 

Purification  of  the  atmosphere, 
140  to  145. 

R. 

Railway  sleepers,  demands  on  for- 
ests for,  89. 
Rain,  100. 

causes  of,  100. 

Huxley  on  the  distribution  of, 

106. 
Maury  on  the  distribution  of, 

107,  108. 
Rainfall,  distribution  of,  102. 

true  index  of  the  wealth  of  a 

country,  94. 

Reclus,      Elis6e,      extract       from 
"Earth,"   67,    68,     69, 
116,  117. 
extract  from  "  Ocean,"  30, 

31,  48,  49. 

Red  River,  raft  in,  67. 
Reforestation,  155  to  159. 
and  deforestation,  14. 
definition  of,  155. 
necessity  for  government   en- 
couragement of,  156. 
objects  of,  155,  156. 


252 


INDEX. 


Keforestation  of  mountains,  French 
code  for,  159,  160, 161,  162, 
163. 
various  methods  employed  in, 

156. 

when  possible,  155,  156. 
Regions,  steppe,  peculiar  distribu- 
tion of  moisture  causing,  43. 
Reservoirs,  definition  of,  109. 
River  basin,  definition  of,  111. 
rafts,  67. 

system,  definition  of,  111. 
Rivers,  cause  of  difference  in  size 

of,  110. 
Roads,  demands  of,  for  removal  of 

forests,  11. 

Rocks,  agencies  causing  disintegra- 
tion of,  52,  53. 
crystalline,  original  source  of 

soil  of,  50. 
disintegration  of,  50. 

influence  of  solvent 
power  of  water  on, 
54,  55. 

influence  of  sprouting 
vegetation  on,  53. 
influence  of  layer  of  decaying 
leaves  on   disintegration  of, 
57. 

Rodents,  influence  of,  on   destruc- 
tion of  forests,  73. 


Sahara  desert,  appearance  of  plants 

on  irrigation  of,  34. 
wadys  in,  34. 
Sand-bars,   damages   produced   by, 

84. 
Sandy  soils,  definition  of,  50,  51. 


Scrub  oak,  appearance  of,  on  burn- 
ing   over    of   pine    forests,    36, 
37. 
Seeding  of  trees,   when  advisable, 

157. 
Seeds,     circumstances     preventing 

germination  of,  40,  41. 
vitality  of,    circumstances  in- 
fluencing, 39  to  41. 
Snow,   protection   afforded   ground 

by,  against  frosts,  129. 
Soil,  alternate   freezing  and  thaw- 
ing, influence  of,  in   forma- 
tion of,  54,  55. 
formation  of,  50,  51. 
influence  of  earthworm  in  for- 
mation of,  56. 

influence  of  erosion  in  forma- 
tion of,  54. 

influence  of  glaciers  in  forma- 
tion of,  54,  59. 
loss  of,  following  destruction  of 

forests,  81,  83,  84. 
necessary  gradual  formation  of, 

56,  57. 
or  cradle,  necessity  of,  for  plant 

growth,  24. 

vegetable,  definition  of,  60. 
Soils,  calcareous,  definition  of,  51. 
classification  of,  50. 
clayey,  definition  of,  50,  51. 
distribution  of,  51,  52,  53. 
gravelly,  definition  of,  50. 
hygroscopic  properties  of,  56. 
influence  of  color  of,  on  power 

of  heat  absorption,  56. 
peaty,  definition  of,  51. 
power  possessed  by,  of  absorb- 
ing gases,  56.    . 
sandy,  definition  of,  50. 


INDEX. 


253 


Sources  of  hydrogen  in  plant  tissue, 

23. 

of  mineral    matters  in  plant 
tissues,  23. 

Species,  domestic  and  domesticated, 
33. 

Springs,  source  of  water  discharged 
by,  109. 

Sprouting  vegetation,  influence  of, 
on  disintegration  of  rocks,  53. 

St.  Helena,  Lyell  on   the   destruc- 
tion of  its  forests,  87. 

Struggle  for  existence  in  the  vege- 
table world,  61. 

Subsoil,  definition  of,  60. 

Sunshine,  influence  of,  in  germina- 
tion of  seeds  of  plants,  21. 

Surface    drainage,    definition     of, 
110. 

Surface,  influence  of,  on  rapidity 
of  evaporation,  91. 

T. 

Temperature  of  air,  influence  of,  on 
rapidity  of  evaporation,  91. 
of  equatorial  and  polar  regions, 
how  balance  is  preserved  be- 
tween, 164,  165. 
Tree-planting,  155  to  159. 

when  advisable,  27. 
Trees,     conditions     necessary    for 

growth  of,  42  to  47. 
Tree-sowing,  157. 
Torrents,  influence  of,  on  destruc- 
tion of  forests,  58. 
Tropical  flora,  why  different  from 
temperate    or    arctic    flora, 

26. 

rains,  how  caused,  102. 
regions,  forests  of,  46. 


Tropical    vegetation,    Guyot's    de- 
scription of,  28,  29,  30. 
Tyndall,  John,  extract  from  "  Heat 
as  a  Mode  of  Motion,"  98,  105, 
134. 
Typographer  beetle,  destruction  of 

forests  by,  75. 
Hough  on,  76,  77. 

U. 

Underground    drainage,   definition 
of,  110. 

V. 

Vacuum,  influence  of,  on  germina- 
tion of  seeds,  40. 
Vapor,  earth's  ocean  of,  90  to  97. 
of   air,  chilling   necessary  for 
precipitation        of, 
100. 

influence  of,  on  econ- 
omy of  the  earth, 
93,  94. 
Vegetable  fibre,  source  of  carbon 

in,  22. 

mould  or  humus,  50. 
world,  struggle  for    existence 

in,  61. 

Vegetation,  agency  of,  in  prevent- 
ing loss  of  soil,  88. 
Velocity  of  wind,  influence  of,  on 

rapidity  of  evaporation,  92. 
Volta's    electrical  theory  of  hail, 
149,  150. 

W. 

Wadys  in  the  Sahara  Desert,  34. 
Water  or  moisture,  necessity  of,  for 
plant  growth,  24. 


22 


254 


INDEX. 


Water,  solvent  power  of,  influence 
of,  in  disintegration  of  rocks, 
54,  55. 

vapor,  screening  influence  of, 
on  sun's  heat,  94. 


Wide  distribution  of  plant  germs, 

30  to  38. 
Wind,  influence  of,  in  destruction 

of  forests,  66. 
Winged  seeds,  32. 


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